Wichern studied theology at Göttingen and Berlin, and, settling in Hamburg, devoted himself to missionary work among the poor. He started a Sunday school which proved very successful, and in 1833 opened his Rauhes Haus at Horn, now a suburb of Hamburg. Wichern traveled through Germany, preaching and establishing hospitals, schools, homes, and rescue stations. He is credited with inventing the (now traditional) Advent wreath in 1839. In 1844, he founded a monthly periodical, Fliegende Blätter des Rauhen Hauses, which he edited.
Through his exertions, the Protestant synod at Wittenberg in 1848 appointed a central committee for home missions. In 1851 the Prussian government made him inspector of prisons and houses of correction, and in 1858 member of the Supreme Ecclesiastical Council, the executive authority of the Evangelical State Church in Prussia. In 1872 disease forced him to retire from office.