 He became a judge of the superior courts of the Dublin circuit in 1914 and 1915.In 1916, Larsen was elected as a Democrat to the 65th United States Congress representing Georgia's 12th congressional district.He was reelected to that position for seven additional terms and did not seek reelection in 1932 as the 12th district became defunct after congressional apportionment reduced Georgia's number of seats in the U.S. House from twelve to ten.