Born at Springfield, IL in 1836, Barrett attended school in St. Louis and Andover, MA, completing his education at St. Louis University. In 1859 he married Miss Anna Farrar Sweringen. They had three children.

Originally a farmer and rancher, Barret became a leader in the St. Louis Agricultural and Mechanical Association following the Civil War. He served as president of that organization from 1866 until 1874. In 1872 he was chosen a presidential elector on the Tilden and Hendrics national ticket.

After two failed attempts to secure the Democratic nomination for mayor, he was finally nominated and elected in 1875. At that time he was only 39 years of age. He became suddenly ill, however, and died a week after his inauguration on April 24, 1875. Burial was at Calvary Cemetery.