Lederer later moved on to stage success in London ("Volpone" 1931, "Autumn Crocus" 1932) and then the United States (again with "Autumn Crocus" and also "The Cat and the Fiddle" 1932). He began making films in Hollywood in 1934, but despite giving light, charming performances in such highly enjoyable confections as "Romance in Manhattan" (1934, opposite Ginger Rogers) and "The Gay Deception" (1935, opposite Frances Dee) didn't quite catch on as an American star. Several of his films toplined the newcomer without the box-office benefit of an established female star opposite him; also, in the increasingly xenophobic and isolationist American culture of the later Depression and early WWII years, it became harder for obviously "foreign" actors, especially those with a certain Continental charm, to make it as film stars.

Lederer continued played leading roles on and off during his film career, which lasted several more decades, but beginning in the late 30s also essayed many character roles, often villainous in nature. During the war years he portrayed Nazis in films like "Confessions of a Nazi Spy" (1939) and in the title role of "The Man I Married" (1940), as the fascist to whom Joan Bennett finds herself wed. One important exception, though, and a most enjoyable throwback to Lederer's matinee idol days, was his highly ingratiating turn as a lady-killer playboy whom Claudette Colbert attracts in order to aid John Barrymore in the masterful Billy Wilder-scripted, Mitchell Leisen-directed "Midnight" (1939). Lederer had kept busy during the 1930s in stage productions outside of New York of works ranging from "Golden Boy" (1937) to "Seventh Heaven" and "No Time for Comedy" (1939) and through the 40s seemed to prefer the wider span of roles he could essay in the theater, touring in "The Play's the Thing" (1942) and "A Doll's House" (1944).

Lederer kept returning to films through the late 50s, however, when a fluffy comedy like "The Ambassador's Daughter" (1956) needed someone tall and classy to play a prince. Some of his most interesting work, though, called on him to bring a flamboyant intensity and menace to films including Jean Renoir's bizarre and fascinating version of the downbeat satirical drama "Diary of a Chambermaid" (1946) and even a pair of modestly budgeted and lower key but still worthy horror items like "The Return of Dracula" (1958, in the title role) and "Terror Is a Man" (1959), the latter his last major film work. Theater work on tour, meanwhile, ranged from "The Sleeping Prince" (1956) to the heroine's father in "The Diary of Anne Frank" (1958).

Lederer was later extremely active in civic affairs, promoting academies for the performing arts, teaching acting and becoming involved in peace movements. He served for a time as Honorary Mayor of Canoga Park, California, where he had made his home, and received many awards for his work in beautifying Los Angeles and serving as Recreation and Parks Commissioner. Lederer occasionally turned up at film festival and museum screenings of his films and in documentaries exploring the work of G.W. Pabst and Louise Brooks. Even as he approached the age of 100, he was still a gracious, vigorous and well-spoken presence carrying plenty of Continental charm from his early stage days as a heartthrob with sensitivity and talent to spare.