Sold into slavery at the age of 12, Crowther was rescued in midpassage by a British cruiser and landed at Sierra Leone, where he was educated in a mission school and baptized. In 1842 he went to the Church Missionary College in London, and received holy orders. Back in the Yoruba country, Crowther worked among his people as a missionary from 1843 to 1851. After accompanying several expeditions to the Niger, he devoted the rest of his life to administrative and evangelistic duties in his newly created diocese of the Niger territories.