UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of January 2026

Commission File Number 001-37928

ChipMOS TECHNOLOGIES INC.

(Translation of Registrant’s Name into English)

No. 1, R&D Rd. 1, Hsinchu Science Park

Hsinchu, Taiwan

Republic of China

(Address of Principal Executive Offices)

(Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.)

Form 20-F ☒ Form 40-F ☐

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Contacts:

ChipMOS REPORTS 23.8% YoY INCREASE IN DECEMBER 2025 REVENUE; 4Q25 REVENUE INCREASES 20.8% YoY

Hsinchu, Taiwan, January 9, 2026 - ChipMOS TECHNOLOGIES INC. (“ChipMOS” or the “Company”) (Taiwan Stock Exchange: 8150 and Nasdaq: IMOS), an industry leading provider of outsourced semiconductor assembly and test services (“OSAT”), today reported its unaudited consolidated revenue for the month of December 2025 and for the fourth quarter ended December 31, 2025. All U.S. dollar figures cited in this press release are based on the exchange rate of NT$31.37 to US$1.00 as of December 31, 2025.

ChipMOS is benefitting from the semiconductor industry’s fundamentally improved cycle position, with continued strong revenue growth in December and the fourth quarter of 2025 led by robust demand for memory products in support of computing and datacenters, combined with a favorable product mix.

Revenue for the fourth quarter of 2025 was NT$6,521.1 million or US$207.9 million, representing an increase of 6.1% from the third quarter of 2025, and an increase of 20.8% from the fourth quarter of 2024.

Revenue for the month of December 2025 was NT$2,203.3 million or US$70.2 million, representing an increase of 2.9% from November 2025, and an increase of 23.8% from December 2024.

About ChipMOS TECHNOLOGIES INC.:

ChipMOS TECHNOLOGIES INC. (“ChipMOS” or the “Company”) (Taiwan Stock Exchange: 8150 and Nasdaq: IMOS) (www.chipmos.com) is an industry leading provider of outsourced semiconductor assembly and test services. With advanced facilities in Hsinchu Science Park, Hsinchu Industrial Park and Southern Taiwan Science Park in Taiwan, ChipMOS is known for its track record of excellence and history of innovation. The Company provides end-to-end assembly and test services to leading fabless semiconductor companies, integrated device manufacturers and independent semiconductor foundries serving virtually all end markets worldwide.

Forward-Looking Statements:

This press release may contain certain forward-looking statements. These forward-looking statements may be identified by words such as ‘believes,’ ‘expects,’ ‘anticipates,’ ‘projects,’ ‘intends,’ ‘should,’ ‘seeks,’ ‘estimates,’ ‘future’ or similar expressions or by discussion of, among other things, strategies, goals, plans or intentions. These statements may include financial projections and estimates and their underlying assumptions, statements regarding current macroeconomic conditions, including the impacts of high inflation, foreign exchange rates and risk of recession, on demand for our products, consumer confidence and financial markets generally; changes in trade regulations, policies, and agreements and the imposition of tariffs that affect our products or operations, including potential new tariffs that may be imposed and our ability to mitigate with respect to future operations, products and services, and statements regarding future performance. Actual results may differ materially in the future from those reflected in forward-looking statements contained in this document, based on a number of important factors and risks, which are more specifically identified in the Company’s most recent U.S. Securities and Exchange Commission (the “SEC”) filings. Further information regarding these risks, uncertainties and other factors are included in the Company’s most recent Annual Report on Form 20-F filed with the SEC and in its other filings with the SEC.