Item 1.01 Entry into a Material Definitive Agreement. On February 27, 2026, Applied Optoelectronics, Inc. (the “ Company”) executed a Standard Form of Agreement Between Owner and Design-Builder (AIA Document A141 - 2024), together with the related Exhibits Package (collectively, the “ Design-Build Agreement”), with LCC3 Solution Inc. (the “ Design-Builder”), effective as of February 13, 2026, pursuant to which the Design-Builder will design and construct the Company’s FAB2 cleanroom project (the “ Project”) at 1111 Gillingham Lane, Sugar Land, Texas 77478. The Project consists of an interior design-build for approximately 92,674 square feet of ISO 6 (Class 1K) certified cleanroom space within an existing warehouse and includes design, engineering, procurement, construction, testing, commissioning, and related closeout activities. The total contract amount for the Project is approximately $30,885,000 (the “ Contract Sum”), inclusive of design, construction, and related professional services, as set forth in the Design-Build Agreement. Payments are generally based on progress, with 10% retainage withheld from each pay application and released upon final completion, subject to final acceptance and completion of punch list items. Pay applications are submitted monthly, and payments are due within 15 days after the Company’s receipt of a properly completed pay application. The Design-Build Agreement provides for liquidated damages in the event of delays in achieving specified key milestones or substantial completion, subject to contractual adjustments and conditions, with an aggregate liquidated damages cap of $1,600,000. The Design-Build Agreement also provides for (i) schedule-based incentives tied to the timely achievement of specified key milestones up to $1,810,000 and (ii) performance-based incentives, including up to $1,724,000 tied to cleanroom validation testing and up to $1,600,000 tied to warranty performance, in each case subject to the conditions and determinations set forth in the Design-Build Agreement. The Project has a targeted Substantial Completion date of September 30, 2026.

Item 2.03 Creation of a Direct Financial Obligation or an Obligation The information contained in Item 1.01 of this Current Report on Form 8-K with respect to the Lease Agreement is incorporated by reference into Item 2.03.

Item 9.01 Financial Statements and Exhibits. (d) Exhibits 10.1 Standard Form of Agreement Between Owner and Design-Builder (AIA Document A141–2024), effective as of February 13, 2026, by and between Applied Optoelectronics, Inc. and LCC3 Solution Inc. 10.2 Exhibits Package to Design-Build Contract (FAB2 Exhibit Package), effective as of February 13, 2026. ────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 104 Cover Page Interactive File (the cover page tags are embedded within the Inline XBRL document). 2 SIGNATURES