Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Dec. 02, 2021	Mar. 31, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2021
Entity File Number	001-36745
Entity Registrant Name	APPLIED DNA SCIENCES INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	59-2262718
Entity Address, Address Line One	50 Health Sciences Drive
Entity Address, City or Town	Stony Brook
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	11790
City Area Code	631
Local Phone Number	240-8800
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	APDN
Security Exchange Name	NASDAQ
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 Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 45.8
Entity Common Stock, Shares Outstanding		7,486,120
Entity Central Index Key	0000744452
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false