Claymont has been a continuous settlement near the mouth of the Naaman's Creek on the Delaware River since at least A.D. 1200, with evidence of its original inhabitants along both banks pointing to the Middle Woodland period (1100-1600 B.C.). The first western inhabitants named the creek and settlement after the Lenape chief who occupied the region. The area developed from a primarily agricultural community in the mid-19th century into a suburban resort area for wealthy Philadelphia families, and in the early 20th century into an industrial working community.

During the colonial period, the town served as a stop along the King’s Highway, and with its location at the confluence of Interstate 95, Interstate 495, Governor Printz Boulevard and Philadelphia Pike, has long been a thoroughfare for travel north) and Washington, D.C. (100 miles to the south).

Claymont was so-named in 1856 upon the efforts of the wife of Reverend Clemson, pastor of the Episcopal church, after they had relocated from their family plantation, Claymont Court, in Charles Town, West Virginia.