Joshua James Guppey was born on August 27, 1820, in Dover, New Hampshire, to John and Hannah Guppey. His father was a farmer. Guppey graduated from Dartmouth College in 1843 and settled in Columbus, Wisconsin, in 1846. He began practicing law soon afterward, and he moved to Portage, Wisconsin, around 1849. By 1850, he was serving as a county judge, and he owned $1,000 of real estate.
Guppey received a commission as a lieutenant colonel in the 10th Wisconsin Infantry on September 13, 1861. On July 25, 1862, he was promoted to colonel of the 23rd Wisconsin Infantry. He was wounded in the left knee on November 3, 1863, in the Battle of Bayou Bourbeaux. He mustered out on July 4, 1865.
Guppey returned to Portage after the war and resumed his service as a county judge. By 1870, he owned $10,000 of real estate and $6,000 of personal property. He died in Portage on December 8, 1893.