Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2025	Mar. 31, 2026	Jun. 30, 2025
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Period End Date	Dec. 31, 2025
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Document Transition Report	false
Entity File Number	814-01399
Entity Registrant Name	Star Mountain Lower Middle-Market Capital Corp
Entity Central Index Key	0001786835
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	86-3924884
Entity Address, Address Line One	140 E. 45th Street
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10017
City Area Code	212
Local Phone Number	810-9044
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	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		10,262,712
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	New York, New York