Cover - shares	9 Months Ended
	Sep. 30, 2024	Nov. 01, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	001-42107
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. Highway 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	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		31,199,099
Entity Central Index Key	0000947559
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false