v3.25.4
Cover - USD ($)
 12 Months Ended
Sep. 30, 2025
Dec. 23, 2025
Mar. 31, 2025
Document Information [Line Items]      
Document Type 10-K    
Document Annual Report true    
Document Transition Report false    
Document Financial Statement Error Correction [Flag] false    
Entity Interactive Data Current Yes    
ICFR Auditor Attestation Flag false    
Amendment Flag false    
Document Period End Date Sep. 30, 2025    
Document Fiscal Year Focus 2025    
Document Fiscal Period Focus FY    
Documents Incorporated by Reference [Text Block] None    
Entity Information [Line Items]      
Entity Registrant Name Citius Oncology, Inc.    
Entity Central Index Key 0001851484    
Entity File Number 001-41534    
Entity Tax Identification Number 99-4362660    
Entity Incorporation, State or Country Code DE    
Current Fiscal Year End Date --09-30    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Shell Company false    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company true    
Entity Ex Transition Period false    
Entity Public Float     $ 5,097,850
Entity Contact Personnel [Line Items]      
Entity Address, Address Line One 11 Commerce Drive    
Entity Address, Address Line Two First Floor    
Entity Address, City or Town Cranford    
Entity Address, State or Province NJ    
Entity Address, Postal Zip Code 07016    
Entity Phone Fax Numbers [Line Items]      
City Area Code (908)    
Local Phone Number 967-6677    
Entity Listings [Line Items]      
Title of 12(b) Security Common Stock, par value $0.0001 per share    
Trading Symbol CTOR    
Security Exchange Name NASDAQ    
Entity Common Stock, Shares Outstanding   84,797,846