UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 10-K

Commission File Number 1-6887

BANK OF HAWAII CORPORATION
(Exact name of registrant as specified in its charter)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:
None

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months, and (2) has been subject to such filing requirements for the past 90 days.

Yes ý    No o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (Section 229.405 of this chapter) is not contained herein, and will not be contained, to the best of registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. o

Indicate by check mark whether the registrant is an accelerated filer (as defined in Rule 12b-2 of the Act.)

Yes ý    No o

The aggregate market value of the registrant's voting stock held by non-affiliates is approximately $1,685,995,541, based on the June 30, 2003 closing price of said stock on the New York Stock Exchange ($33.15 per share).

As of February 20, 2004, there were 54,699,024 shares of Common Stock outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Proxy Statement relating to the Annual Meeting of Shareholders to be held April 30, 2004, are incorporated by reference into Part III of this Report.

Bank of Hawaii Corporation

Form 10-K

INDEX

PART I

Item 1.    Description of Business

General

Bank of Hawaii Corporation (the "Company") is a Delaware corporation and a bank holding company.

The Company's banking subsidiary, Bank of Hawaii (the "Bank"), was organized under the laws of Hawaii on December 17, 1897 and has its headquarters in Honolulu, Hawaii. Its deposits are insured by the Federal Deposit Insurance Corporation (the "FDIC"). The only other subsidiary of the Company is Bancorp Hawaii Capital Trust I, a guarantor trust.

Through the Bank, the Company provides a diversified range of banking financial services and products primarily in Hawaii and the Pacific Islands (Guam and nearby islands and American Samoa). The Bank's subsidiaries include Bank of Hawaii Leasing, Bankoh Investment Services, Pacific Century Life Insurance Company, Triad Insurance Agency, Bank of Hawaii Insurance Services, and Bank of Hawaii International. The Bank's subsidiaries are engaged in equipment leasing, insurance and insurance agency services, securities brokerage and investment services.

The Company is aligned into the following business segments: Retail Banking, Commercial Banking, Investment Services Group, and Treasury and Other Corporate. Additional financial and other information about the Company's business segments is presented in the Business Segments section of Management's Discussion and Analysis of Financial Condition and Results of Operations ("MD&A") and Note 18 to the Consolidated Financial Statements in this report, which is incorporated by reference in this Item.

The Company divested most of its foreign operations by the end of 2001. Additional information on foreign activities are presented in Table 12 of MD&A and Note 19 to the Consolidated Financial Statements in this report, which is incorporated by reference in this Item.

The Company's annual report on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, and all amendments to those reports can be found on its internet site at http://www.boh.com as soon as reasonably practicable after such material is electronically filed with or furnished to the Securities and Exchange Commission (the "SEC"). The SEC maintains an internet site, http://www.sec.gov, that contains reports, proxy and information statements and other information regarding issuers that file electronically with the SEC.

The Company's Corporate Governance Guidelines, the Charters of the Audit Committee, the Human Resources and Compensation Committee, the Executive and Strategic Planning Committee, and the Nominating and Corporate Governance Committee and the Code of Business Conduct and Ethics will be available on the Company's website by April 30, 2004. Upon written request to the Corporate Secretary at 130 Merchant Street, Honolulu, Hawaii, 96813, the information is available in print to any shareholder.

Competition

The Company, the Bank and its subsidiaries are subject to substantial competition from banks, savings associations, credit unions, mortgage companies, finance companies, mutual funds, brokerage firms, insurance companies and other providers of financial services, including financial service subsidiaries of commercial and manufacturing companies. The Company also competes with certain non-financial institutions and governmental entities that offer financial products and services. Some of the Company's competitors are not subject to the same level of regulation and oversight that are required of banks and bank holding companies.

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Supervision and Regulation

The following discussion describes certain material elements of an extensive regulatory framework applicable to bank holding companies and their subsidiaries and provides certain information specific to the Company.

This regulatory framework is intended primarily for the protection of depositors, federal deposit insurance funds and the banking system as a whole, and not for the protection of security holders. To the extent that this information describes statutory and regulatory provisions, it is qualified in its entirety by reference to those provisions. Any change in applicable laws or regulations may have a material effect on the business of the Company and its subsidiaries.

The Company is registered as a bank holding company ("BHC") under the Bank Holding Company Act of 1956, as amended (the "BHC Act"), and is subject to the supervision of and to examinations by the Board of Governors of the Federal Reserve Bank System (the "FRB"). The Company is also registered as a bank holding company under the Hawaii Code of Financial Institutions (the "Code") and is subject to the registration, reporting, and examination requirements of the Code.

The BHC Act prohibits, with certain exceptions, a BHC from acquiring beneficial ownership or control of more than 5% of the voting shares of any company, including a bank, without the FRB's prior approval and from engaging in any activity other than those of banking, managing or controlling banks or other subsidiaries authorized under the BHC Act, or furnishing services to or performing services for its subsidiaries. Among the permitted activities is the ownership of shares of any company the activities of which the FRB determines to be so closely related to banking or managing or controlling banks as to be a proper incident thereto.

Subject to certain limits, under the Riegle-Neal Interstate Banking and Branching Efficiency Act (the "Riegle-Neal Act") an adequately capitalized and adequately managed BHC may acquire control of banks in any state. An interstate acquisition may not be approved if immediately following the acquisition the BHC would control 30 percent or more of the total FDIC-insured deposits in that state (or such lesser or greater amount set by the state), unless the acquisition is the BHC's initial entry into the state. An adequately capitalized and adequately managed bank may apply for permission to merge with an out-of-state bank and convert all branches of both parties into branches of a single bank. An interstate bank merger may not be approved, if immediately following the acquisition, the acquirer would control 30 percent or more of the total FDIC-insured deposits in that state (or such lesser or greater amount set by the state), unless the acquisition is the acquirer's initial entry into the state. Banks are also permitted to open newly established branches in any state in which it does not already have banking branches if such state enacts a law permitting such de novo branching.

Hawaii has enacted a statute that authorizes out-of-state banks to engage in mergers with Hawaii banks or acquisitions of substantially all of their assets, following which any such out-of-state bank may operate the branches of the Hawaii bank it has acquired. The Hawaii bank must have been in continuous operation for at least five years unless it is subject to or in danger of becoming subject to certain types of supervisory action. This statute does not permit out-of-state banks to acquire branches of Hawaii banks other than through an "interstate merger transaction" under the Riegle-Neal Act (except in the case of a bank that is subject to or in danger of becoming subject to certain types of supervisory action) or to open branches in Hawaii on a de novo basis.

Under the Gramm-Leach-Bliley Act, a BHC may elect to become a financial holding company and thereby engage in a broader range of financial and other activities than are permissible for traditional BHCs. In order to qualify for the election, all of the depository institution subsidiaries of the BHC must be well capitalized and well managed and all of its insured depository institution subsidiaries must have achieved a rating of "satisfactory" or better under the Community Reinvestment Act. Financial holding companies are permitted to engage in activities that are "financial in nature" or incidental or complementary thereto

3

as determined by the FRB. The Gramm-Leach-Bliley Act identifies several activities as "financial in nature," including, among others, insurance underwriting and agency, investment advisory services, merchant banking and underwriting and dealing or making a market in securities. The Company has not elected to become a financial holding company.

Subsidiary Bank

The Bank is subject to supervision and examination by the Federal Reserve Bank of San Francisco and the State of Hawaii Department of Commerce and Consumer Affairs Division of Financial Institutions. Depository institutions, including the Bank, are subject to extensive federal and state regulation that significantly affect their business and activities. Regulatory bodies have broad authority to implement standards and to initiate proceedings designed to prohibit depository institutions from engaging in unsafe and unsound banking practices. The standards relate generally to operations and management, asset quality, interest rate exposure and executive compensation. The agencies are authorized to take action against institutions that fail to meet such standards.

Source of Strength Doctrine

Under FRB policy, a BHC is expected to serve as a source of financial and management strength to its subsidiary banks and to commit resources to support its subsidiary banks in circumstances where it might not do so absent such a policy. This support may be required at times when the BHC may not have the resources to provide it. Under this policy, a BHC is expected to stand ready to use available resources to provide adequate capital funds to its subsidiary banks during periods of financial adversity and to maintain the financial flexibility and capital-raising capacity to obtain additional resources for assisting its subsidiary banks.

Capital Requirements

The Company and the Bank are subject to risk-based capital requirements and guidelines imposed by the banking regulatory agencies.

As an additional means to identify problems in the financial management of depository institutions, the Federal Deposit Insurance Corporation Improvement Act ("FDICIA") requires federal bank regulatory agencies to establish certain non-capital safety and soundness standards.

FDICIA requires federal bank regulatory agencies to take "prompt corrective action" with respect to FDIC-insured depository institutions that do not meet minimum capital requirements. A depository institution's treatment for purposes of the prompt corrective action provisions will depend upon how its capital levels compare to various capital measures and certain other factors, as established by regulation.

For further information regarding the minimum capital requirements applicable to the Company and the Bank, see Note 11 to the Consolidated Financial Statements, which is incorporated by reference in this Item.

Dividend Restrictions

The Company is a legal entity separate and distinct from the Bank. The Company's principal source of funds to pay dividends on its common stock and debt service on its debt is dividends from the Bank. Various federal and state statutory provisions and regulations limit the amount of dividends the Bank may pay to the Company without regulatory approval, including requirements to maintain capital above regulatory minimums. The FRB is authorized to determine the circumstances when the payment of dividends would be an unsafe or unsound practice and to prohibit such payments. The right of the Company, its stockholders and creditors to participate in any distribution of the assets or earnings of its subsidiaries also is subject to the prior claims of creditors of those subsidiaries.

4

For information regarding the limitations on Bank dividends, see Note 11 to the Consolidated Financial Statements, which is incorporated by reference in this Item.

Other Transfers of Funds

The Bank is subject to restrictions under federal law that limit the transfer of funds or other items of value to the Company and any non-bank subsidiaries (including affiliates) in so-called "covered transactions." In general, covered transactions include loans and other extensions of credit, investments and asset purchases, as well as other transactions involving the transfer of value from the Bank to an affiliate or for the benefit of an affiliate. Unless an exemption applies, covered transactions by the Bank with a single affiliate are limited to 10% of the Bank's capital and surplus and, with respect to all covered transactions with affiliates in the aggregate, to 20% of the Bank's capital and surplus.

FDIC Insurance

The FDIC has adopted a premium schedule under which the actual assessment rate for a particular institution depends in part upon the risk classification the FDIC assigns to that institution. The FDIC may increase an institution's insurance premiums or terminate insurance upon a finding that the institution has engaged in unsafe and unsound practices.

Employees

At January 31, 2004, the Company and its subsidiaries had approximately 2,700 employees.

Item 2.    Properties

The principal offices of the Company and each of its business segments are located in the Financial Plaza of the Pacific building in Honolulu, Hawaii, which is owned primarily by the Company. The land under the office building is leased. The Company and its subsidiaries own and lease other premises, consisting of branch offices and operating facilities located in Hawaii and the Pacific Islands which are primarily used by the Retail Banking and Commercial Banking business segments.

Item 3.    Legal Proceedings

The Company and its subsidiaries are defendants in various legal proceedings arising from normal business activities. In the opinion of management, after reviewing these proceedings with counsel, the aggregate liability, if any, resulting from these proceedings is not expected to have a material effect on the Company's consolidated financial position or results of operations.

Item 4.    Submission of Matters to a Vote of Security Holders

No matter was submitted during the fourth quarter of 2003 to a vote of security holders through solicitation of proxies or otherwise.

5

Executive Officers of Registrant:

All listed officers are executive officers of the Company and the Bank.

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PART II

Item 5.    Market for the Registrant's Common Equity and Related Stockholder Matters

The common stock of the Company is traded on the New York Stock Exchange (NYSE Symbol: BOH) and quoted daily in leading financial publications. As of February 20, 2004, there were 9,653 common shareholders of record.

Information regarding the historical market prices of the Company's common stock and dividends declared on that stock are included below.

Market Prices, Book Values and Common Stock Dividends Per Share

The Board of Directors of the Company considers on a quarterly basis the feasibility of paying a cash dividend to its shareholders. General practice is to declare a dividend in the beginning of a quarter to be paid prior to the end of the quarter and is based, in part, on the expected earnings for the quarter. For additional information regarding the limitation on the Company's ability to pay dividends, see "Dividend Restrictions" under "Supervision and Regulations" in Item 1 of this report and Note 11 to the Consolidated Financial Statements, which are incorporated by reference in this Item.

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Item 6.    Selected Financial Data

Summary of Selected Consolidated Financial Data¹

¹

Comparison between years is affected by divestitures that occurred in 2001.

²

Table 7 in Item 7, provides a reconciliation of these non-GAAP disclosures and is incorporated by reference in this Item.

n.m.—not meaningful.

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Item 7.    Management's Discussion and Analysis of Financial Condition and Results of Operations

Forward-Looking Statements

This report contains forward-looking statements concerning, among other things, the economic environment in the Company's service area, the expected level of loan loss provisioning, anticipated savings of our systems replacement project, the effect of our new three-year plan, and anticipated dividends, revenues and expenses during 2004 and beyond. The Company believes the assumptions underlying its forward-looking statements are reasonable. However, any of the assumptions could prove to be inaccurate and actual results may differ materially from those projected for a variety of reasons, including, but not limited to: 1) unanticipated changes in business and economic conditions, the competitive environment, fiscal and monetary policies, or legislation in Hawaii and the other markets the Company serves; 2) changes in the Company's credit quality or risk profile which may increase or decrease the required level of allowance for loan and lease losses; 3) changes in market interest rates that may affect the Company's credit markets and ability to maintain its net interest margin; 4) changes to the amount and timing of the Company's anticipated equity repurchases; 5) inability to achieve expected benefits of the Company's business process changes due to adverse changes in implementation processes or costs, operational savings, or timing; 6) real or threatened acts of war or terrorist activity affecting business conditions; and 7) adverse weather and other natural conditions impacting the Company and its customers' operations. Words such as "believes," "anticipates," "expects," "intends," "targeted" and similar expressions are intended to identify forward-looking statements but are not exclusive means of identifying such statements. The Company does not undertake any obligation to update forward-looking statements to reflect later events or circumstances.

Critical Accounting Policies

The Company's Consolidated Financial Statements were prepared in accordance with accounting principles generally accepted in the United States and follow general practices within the financial services industry it operates. The most significant accounting policies followed by the Company are presented in Note 1 to the Consolidated Financial Statements, which is incorporated by reference in this Item. Application of these principles requires management to make estimates, assumptions and judgments that affect the amounts reported in the financial statements. Critical accounting estimates are defined as those that require assumptions to be made that are "highly uncertain" at the time the estimate was made and where the impact of the selection of the estimate or a change in the estimate from period to period would have a material impact on the financial statements. Based on the potential impact to the financial statements of the valuation methods, estimates, assumptions and judgments used, management identified the determination of the Allowance for Loan and Lease Losses (the "Allowance"), the valuation of mortgage servicing rights and the valuation of leased asset residuals to be the accounting estimates that are the most subjective and/or judgmental.

Allowance for Loan and Lease Losses

The Company maintains an Allowance in an amount adequate to cover management's estimate of probable credit losses based on analyses of historical loss experience supplemented by judgmental expectations of the impact of economic conditions as of a given balance sheet date. The determination of the amount of the Allowance is a critical accounting estimate as it requires the use of estimates and significant judgment related to the amount and timing of expected future cash flows on impaired loans, estimated loss rates on homogenous portfolios and deliberation on economic factors and trends. It is possible that the Allowance could have been reduced or increased if the Company had judged economic conditions and other factors and risks to be more or less favorable. See further discussion on Allowance in "Corporate Risk Profile—Allowance for Loan and Lease Losses."

9

Mortgage Servicing Rights Valuation

When mortgage loans are sold with servicing retained, a servicing asset is established and accounted for based on estimated fair values. Such values are determined using discounted cash flow modeling techniques, which require management to make estimates and assumptions regarding the amount and timing of expected future cash flows, loan repayment rates, costs to service and interest rates that contemplate the risk involved. Because the value of these assets is sensitive to changes in the estimates and assumptions made, the valuation of mortgage servicing rights is considered a critical accounting estimate. Had the Company assumed that interest rates would decrease and prepayment rates remain at record high levels, then the value of the mortgage servicing rights could have been lower. Note 6 to the Consolidated Financial Statements, which includes further discussion on the accounting for these assets and a sensitivity analysis, is incorporated by reference in this Item.

Residual Valuation of Leased Assets

Lease financing receivables include a residual value component, which represents the estimated value of leased assets upon lease expirations. The valuation of leased assets is considered a critical accounting estimate due to the subjectivity surrounding the future valuation. The determination of expected value at lease termination is derived from a variety of sources, including equipment valuation services, appraisals and publicly available market data on recent sales transactions on similar equipment. The length of time until termination and the cyclical nature of equipment values are important variables considered in making this determination. Residual values could have been lower, therefore reducing the value of the recorded leases, if the Company had assumed that current uncertainties in the airline industry would continue indefinitely or that there will be a greater incidence of airlines using the bankruptcy process to lower aircraft lease rates or eliminate unused aircraft. These values could also affect the level of the Allowance. Note 5 to the Consolidated Financial Statements includes further discussion on the accounting for these assets and is incorporated by reference in this Item.

Overview

The end of 2003 marked the successful completion of the Company's 2001-2003 strategic plan. The objectives of this plan were to: improve credit risk management; intelligently allocate capital resources; solidify performance in core markets; improve customer service; increase financial returns; and maintain a strong capital position. The Company undertook several initiatives in an effort to meet these objectives, the most significant of which were: (1) the credit risk management process was strengthened and the quality of the Company's credit portfolios was improved; (2) underperforming businesses, including banking operations in California, Asia and the South Pacific, were divested in 2001; (3) the Information Technology Systems Replacement Project ("Systems Replacement Project") was completed in 2003 and has resulted in lower operating costs, an integrated technology platform and improved customer service; and (4) a share repurchase program, which began in July 2001 returned excess capital to the shareholders. Each of these initiatives is further discussed in the following sections of this report.

Net income for 2003 was $135.2 million, or $2.21 per diluted share, compared to $121.2 million, or $1.70 per diluted share, in 2002. For the year, the net interest margin increased 24 basis points to 4.23%, largely due to improvements in the mix of deposit liabilities and a lower cost of funds. The Company did not recognize a provision for loan and lease losses in 2003. Non-interest income for 2003 of $198.7 million increased slightly from 2002; however the individual components changed as fee and insurance income improved while the low interest rate environment and stock market performance led to a decline in mortgage banking income and income from trust and asset management, respectively. Non-interest expenses for 2003 decreased 3% to $357.9 million from $369.2 million in 2002. Excluding the costs of the Systems Replacement Project, the Company achieved a 6% reduction in non-interest expenses in 2003 from 2002.

10

Analysis of Statement of Income

Comparisons between 2002 and 2001 may not be meaningful due to the divestiture of businesses in 2001. Certain 2002 and 2001 information has been reclassified to conform to 2003 presentation.

Net Interest Income

Net interest income on a taxable equivalent basis decreased by $4.4 million or 1% from 2002. The decrease in net interest income was primarily a result of the lower interest rate environment, in particular the low interest rates earned on mortgage loans and short-term investments which were at the lowest levels in several decades. The lower level of interest income was partially offset by a reduction in interest expense, including a reduction in interest paid on deposits, which declined by 44% in spite of a 5% increase in average interest bearing deposits, and interest paid on short and long-term borrowings, which decreased due to a reduction in the borrowings.

Average interest earning assets in 2003 decreased $617.2 million, or 7%, from 2002 primarily due to an $872.7 million decrease in Interest Bearing Deposits which was used for stock repurchases and debt reductions. Average interest bearing liabilities in 2003 decreased $536.3 million or 8% from 2002 mainly due to reductions in short-term borrowings and long-term debt.

The net interest margin was 4.23% in 2003, a 24 basis point increase from 3.99% in 2002. The improvement was attributable to extending the maturities of certain short-term investments and reductions in time deposits, short-term borrowings and debt, all of which lowered the Company's cost of funds.

Average balances, related income and expenses, and resulting yields and rates are presented in Table 1. An analysis of changes in net interest income is presented in Table 2.

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Table 1
Consolidated Average Balances and Interest Rates—Taxable Equivalent Basis

¹

Certain 2002 and 2001 information has been reclassified to conform to 2003 presentation.

²

Non-performing loans are included in the respective average loan balances. Income, if any, on such loans is recognized on a cash basis.

³

Interest income includes taxable-equivalent basis adjustment based upon a statutory federal tax rate of 35%.

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Table 2
Analysis of Changes in Net Interest Income—Tax Equivalent Basis