Document And Entity Information - USD ($)	12 Months Ended
	Jun. 30, 2021	Aug. 31, 2021	Dec. 31, 2020
Document Information [Line Items]
Entity Central Index Key	0000763532
Entity Registrant Name	LSI INDUSTRIES INC
Amendment Flag	false
Current Fiscal Year End Date	--06-30
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2021
Document Type	10-K
Document Annual Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	0-13375
Entity Incorporation, State or Country Code	OH
Entity Address, Address Line One	10000 Alliance Road
Entity Address, City or Town	Cincinnati
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45242
Entity Tax Identification Number	31-0888951
City Area Code	513
Local Phone Number	793-3200
Title of 12(b) Security	Common shares, no par value
Trading Symbol	LYTS
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	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 206,799,551
Entity Common Stock, Shares Outstanding		26,596,438
ICFR Auditor Attestation Flag	true