He was born in Vienna as Ferdinand Maximilan Charles Leopold Marie, Duke of Saxony, later becoming Prince of Saxe-Coburg-Gotha, the son of Augustus of Saxe-Coburg-Kohary (1818–1881) and his wife née Clémentine of Orléans (1817–1907). He was proclaimed prince regnant of Bulgaria on 25 June 1887 (O.S.)/7 July 1887 (N.S.).