Miton Rosmer made his name on the British stage, debuting in 1889. He easily made the transition to silent pictures, appearing in such films as The Passionate Friends (1922). Talkies proved to be no obstacle to him, as it did to many silent actors, and Rosmer had roles in such classics as Goodbye, Mr. Chips (1939) and The Stars Look Down (1940). He specialized in playing such characters as magistrates, professors, army officers and other authority figures.

Rosmer was also a screenwriter and director. The Crimean War epic Balaclava (1928), which had been shot as a silent by Maurice Elvey, was extensively reshot by Rosmer as a talkie, and he also directed such other films as Channel Crossing (1933), The Great Barrier (1937) and Emil and the Detectives (1935). His final film as an actor was John Wesley (1954), after which he worked in television until 1956, when he retired. He died at age 90 in 1971.