Born in Pittsburgh and raised largely in Philadelphia, Tanner studied at the Pennsylvania Academy of the Fine Arts under Thomas Eakins. He moved to France in 1891 and studied at the Academie Julian in Paris. His early paintings included scenes of African American family life, but he became internationally known for religious subjects.
Tanner visited Palestine to study the settings of biblical narratives. His paintings combine careful observation of human figures with evocative light and a contemplative mood. He received major recognition at the Paris Salon and continued working in France until his death in 1937.