Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Feb. 22, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	000-22507
Entity Registrant Name	THE FIRST BANCSHARES, INC.
Entity Incorporation, State or Country Code	MS
Entity Tax Identification Number	64-0862173
Entity Address, Address Line One	6480 U.S. Hwy. 98 West, Suite A
Entity Address, City or Town	Hattiesburg
Entity Address, State or Province	MS
Entity Address, Postal Zip Code	39402
City Area Code	601
Local Phone Number	268-8998
Title of 12(b) Security	Common Stock
Trading Symbol	FBMS
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	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 558.5
Entity Common Stock, Shares Outstanding		31,063,780
Auditor Firm ID	686
Auditor Name	FORVIS, LLP
Auditor Location	Jackson, MS
Entity Central Index Key	0000947559
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false