Benjamin was the son of George Benjamin and Elizabeth Curtis Green Carpenter.
Benjamin married Helen Graham Fairbank September 18, 1893, in Chicago.
Benjamin graduated from Harvard in 1888, and succeeded his father as President of George B, Carpenter Company, in 1913. During WWi Benjamin was commissioned a Captain and rose to the rank of Major in the U.S. Army. He was on active duty from July 1917 to February 1919.