He was the son of Parley P. Pratt and wife Mary Wood, the father of Rey L. Pratt, the grandfather of Michigan governor George W. Romney, and the great-grandfather of Massachusetts governor Mitt Romney. He was born in a covered wagon during a one-hour stopover on the Mormon Trail near Mount Pisgah, Iowa.
Brother Pratt was one of the first missionaries to Mexico, and in 1876 at Hermosillo, Sonora, Pratt and Meliton Trejo performed the first baptisms recorded by the LDS Church in that country. Pratt latter served as president of the Mexican Mission based in Mexico City for part of the 1880s. After his release he moved to Colonia Dublan in Galeana, state of Chihuahua, Mexico, where he died.
Brother Pratt married in Salt Lake City, Utah, 20 April 1874 Anna Johanna Dorothy ("Dora") Wilcken (Dahme, Zarpin, Rheinfeld, Ostholstein, Schleswig-Holstein, 25 July 1854 - Colonia Dublán, Galeana, Chihuahua, Mexico, 22 June 1929), daughter of Carl Heinrich Wilcken (Eckhorst, Holstein, Schleswig-Holstein, 5 October 1831 - Salt Lake City, Utah, 9 April 1914) and (m. Neustadt in Holstein, Ostholstein, Schleswig-Holstein, 10 August 1853) Eliza Christina Carolina Reiche (Neustadt in Holstein, Ostholstein, Schleswig-Holstein, 1 May 1830 - Salt Lake City, Utah, 13 August 1906), both of whom also became LDS Church members.