Jacob Hamblin was born 6 April 1819 in Ashtabula County, Ohio. His parents were farmers, and he learned farming a youth. In 1836 his family moved to Wisconsin Territory and homesteaded at a place called Spring Prairie. Hamblin's father told Jacob when he was nineteen that he had been a faithful boy and that it was time for him to go into the world and do something for himself. Hamblin then traveled more than a hundred miles west and went to work in the Galena mines. After working for a few months, he barely escaped a rockfall that killed his co-worker. The incident gave him an aversion to mining, and he never returned to the mines. Collecting his wages, he returned to Wisconsin and paid for the land he had helped homestead.

In the autumn of 1839 he married Lucinda Taylor and settled down to start a family. However, in February 1842 he heard that Mormon elders were preaching nearby. After listening to the Mormon preaching, he joined the Mormon Church on 3 March 1842. Hamblin started missionary work almost immediately and became known as a faith healer, showing the signs of "those that believe," in his words. The next year he moved to Nauvoo, Illinois, where the Mormon Church headquarters were located.