Parley Parker Pratt was born in Burlington, Ostego County, New York, on 12 April 1802, the middle son of five born to Jared and Charity Pratt. At a young age he was required to work to help sustain the family, which limited his formal education. His mother taught him to read the Bible at home, where, he claimed, Christian virtues were taught by example. He became a voracious reader. When he was sixteen and boarding with his father's sister, he had his last opportunity for formal schooling.
He married Thankful Halsey on 9 September 1827. He cleared some land and built a small cabin in Amherst, Lorain County, Ohio, where they resided. After hearing Sydney Rigdon preach, he joined the Society of Reformed Baptists and felt constrained to sell his worldly goods and become a missionary.
He transferred his missionary zeal to the Church of Jesus Christ of Latter-day Saints, into which he was baptized 1 September 1830. Pratt preached at every opportunity, and served missions from England to the Pacific Islands to Chile, as well as in many areas of the United States and in several counties of Utah.