v3.26.3
Cover
 12 Months Ended
Jun. 30, 2026
shares
Document Information [Line Items]  
Document Type 20-F
Document Annual Report true
Document Transition Report false
Document Financial Statement Error Correction [Flag] false
Document Shell Company Report false
Entity Interactive Data Current Yes
Document Accounting Standard U.S. GAAP
ICFR Auditor Attestation Flag true
Amendment Flag false
Document Period End Date Jun. 30, 2026
Document Fiscal Year Focus 2026
Document Fiscal Period Focus FY
Document Registration Statement false
Current Fiscal Year End Date --06-30
Entity File Number 001-40617
Entity Registrant Name REGENCELL BIOSCIENCE HOLDINGS LIMITED
Entity Address, Address Line One 9/F Chinachem Leighton Plaza
Entity Address, Address Line Two 29 Leighton Road
Entity Address, City or Town Causeway Bay
Entity Address, Country HK
Title of 12(b) Security Ordinary shares, par value $0.00001
Trading Symbol RGC
Security Exchange Name NASDAQ
Entity Common Stock, Shares Outstanding 495,884,376
Entity Well-known Seasoned Issuer Yes
Entity Voluntary Filers No
Entity Current Reporting Status Yes
Entity Filer Category Large Accelerated Filer
Entity Emerging Growth Company false
Entity Shell Company false
Entity Central Index Key 0001829667
Entity Address, Postal Zip Code 0000
Entity Incorporation, State or Country Code E9
Business Contact  
Document Information [Line Items]  
Entity Address, Address Line One 9/F Chinachem Leighton Plaza
Entity Address, Address Line Two 29 Leighton Road
Entity Address, City or Town Causeway Bay
Entity Address, Country HK
Contact Personnel Name Yat-Gai Au
City Area Code 852
Local Phone Number 2155 0823
Entity Address, Postal Zip Code 000