The discovery of samarium is attributed to Boisbaudran, who accomplished the separation of samaria from a rare-earth (cerium and lanthanum) mixture called didymia, obtained by Mosander in 1879. In fact, the Boisbaudran's samaria was a samarium and europium mixture, separated in 1901 by Demarcay.

The denomination samarium derives from the name of the ore smarskite, named after the Russian officer Samarski.