Sebastian County, Arkansas
![](/Images/godic/202502/09/Sebastian_County_Courthouse-Ft._Smith_City_Hall,_Southeast_View0227.JPG")
![Map of Arkansas highlighting Sebastian County](/Images/godic/202502/09/Map_of_Arkansas_highlighting_Sebastian_County.svg0227.png")
![Map of the United States highlighting Arkansas](/Images/godic/202502/09/Map_of_USA_AR.svg0227.png")
![Age pyramid Sebastian County[10]](/Images/godic/202502/09/USA_Sebastian_County,_Arkansas_age_pyramid.svg0228.png")
Sebastian County is a county located in the U.S. state of Arkansas. As of the 2010 census, the population was 125,744, making it the fourth-most populous county in Arkansas. The county has two county seats, Greenwood and Fort Smith.
Sebastian County is part of the Fort Smith, AR-OK Metropolitan Statistical Area.