A pharmacist, Earhart was the Twelfth Ward leader of the Regular Democratic Organization political machine.

He was elected to New Orleans' commission council in 1930, where he served as Commissioner of Public Utilities.

Earhart was one of three acting mayors who served in the summer of 1936 between the resignation of T. Semmes Walmsley and the accession of Robert Maestri.

After his brief tenure as acting mayor, Earhart continued to serve as Commissioner of Public Utilities in the Maestri administration.

Earhart owned and founded the first drugstore chain in New Orleans.