v3.26.1
Document And Entity Information
 12 Months Ended
Mar. 31, 2026
shares
Document Information Line Items  
Entity Central Index Key 0002030834
Document Type 20-F
Document Registration Statement false
Document Annual Report true
Current Fiscal Year End Date --03-31
Document Period End Date Mar. 31, 2026
Document Fiscal Year Focus 2026
Document Transition Report false
Document Shell Company Report false
Entity File Number 001-42457
Entity Registrant Name OneConstruction Group Limited
Entity Incorporation, State or Country Code E9
Entity Address, Address Line One Unit 11, 5/F, Tower 1, Harbour Centre
Entity Address, Address Line Two 1 Hok Cheung Street, Hunghom
Entity Address, City or Town Kowloon
Entity Address, Country HK
Title of 12(b) Security Ordinary Shares
Trading Symbol ONEG
Security Exchange Name NASDAQ
Entity Common Stock, Shares Outstanding 16,000,000
Entity Well-known Seasoned Issuer No
Entity Voluntary Filers No
Entity Current Reporting Status Yes
Entity Interactive Data Current Yes
Entity Filer Category Non-accelerated Filer
Entity Emerging Growth Company true
Entity Ex Transition Period false
ICFR Auditor Attestation Flag false
Document Financial Statement Error Correction [Flag] false
Document Accounting Standard U.S. GAAP
Entity Shell Company false
Auditor Opinion [Text Block]

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of OneConstruction Group Limited and its subsidiaries (collectively, the “Group”) as of March 31, 2026 and 2025, the related consolidated statements of operations and comprehensive income (loss), changes in shareholders’ equity, and cash flows for each of the three years ended March 31, 2026, and the related notes to the consolidated financial statements (collectively, the financial statements). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Group as of March 31, 2026 and 2025, and the results of its operations and its cash flows for each of the three years ended March 31, 2026, in conformity with accounting principles generally accepted in the United States of America.
Auditor Name Audit Alliance LLP
Auditor Location Singapore
Auditor Firm ID 3487
Amendment Flag false
Document Fiscal Period Focus FY
Entity Address, Postal Zip Code 00000
Business Contact [Member]  
Document Information Line Items  
Entity Address, Address Line One Unit 11, 5/F, Tower 1, Harbour Centre
Entity Address, Address Line Two 1 Hok Cheung Street, Hunghom
Entity Address, City or Town Kowloon
Entity Address, Country HK
Contact Personnel Name Ka Chun Gordon Li
City Area Code (+852)
Local Phone Number 2123 8400
Contact Personnel Email Address gli@oneconstruction.com.hk
Entity Address, Postal Zip Code 00000