Moving to Walterboro after his admission to the bar, he practiced law and was elected probate judge of Colleton County in 1918.

In the senate, he became associated with a group of like-minded legislators, largely from the rural South Carolina lowcountry, that was known as the "Barnwell Ring".

Due to their legislative seniority, these fiscal conservatives held most of the political power in South Carolina from the 1930s to the 1960s.

He promoted industrial development, and appointed a study commission to recommend ways to transition the state from a wartime to a peacetime economy at the end of the war.

He was not a candidate for election to a full term as governor in 1942, instead choosing to run for his old seat in the state senate.