Document And Entity Information - USD ($)
$ in Millions
12 Months Ended
Sep. 30, 2019
Dec. 16, 2019
Mar. 29, 2019
Document And Entity Information      
Entity Registrant Name Outlook Therapeutics, Inc.    
Entity Central Index Key 0001649989    
Trading Symbol ons    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Voluntary Filers No    
Current Fiscal Year End Date --09-30    
Entity Shell Company false    
Entity Filer Category Non-accelerated Filer    
Entity Well-known Seasoned Issuer No    
Entity Public Float     $ 18.9
Entity Common Stock, Shares Outstanding   30,103,173  
Document Type 10-K    
Document Period End Date Sep. 30, 2019    
Amendment Flag false    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Entity Small Business true    
Entity Emerging Growth Company true    
Entity Ex Transition Period true