Askin immigrated to the United States in 1940 and, served in World War II as a Staff Sergeant in the US Army Air Forces. After the war, he went to Hollywood to begin a career in films, invariably portraying foreign characters who speak English with a strong accent. Askin appeared as the Russian Composer Anton Rubinstein in a Disneyland anthology episode of the life of Peter Tchaikovsky. Fans of the television series Adventures of Superman recall his portrayals of an eastern European Diamond smuggler (Joseph Ferdinand) in the 1953 black-and-white episode "Superman in Exile", and as a South American prime minister in a color episode. He appeared in 20th Century Fox's biblical epic The Robe in 1953 as a Syrian guide named Abidor. In 1960, he appeared in the film Pension Schöller, and the following year was prominently featured in Billy Wilder's film One, Two, Three, co-starring with James Cagney.

His other film credits include roles in Road to Bali (1952), Desert Legion (1953), The Veils of Bagdad (1953), Knock on Wood (1954), Secret of the Incas (1954), Valley of the Kings (1954), Son of Sinbad (1955), The Last Blitzkrieg (1959), Lulu (1962), Sherlock Holmes and the Deadly Necklace (1962), Do Not Disturb (1965), What Did You Do in the War, Daddy? (1966), Double Trouble (1967), The Caper of the Golden Bulls (1967), The Perils of Pauline (1967), The Wicked Dreams of Paula Schultz (1968), A Fine Pair (1968), Guns for San Sebastian (1968), The Maltese Bippy (1969), Death Knocks Twice (1969), Hammersmith Is Out (1972), The World's Greatest Athlete (1973), Going Ape! (1981), and Frightmare (1983). In 1982 he had a brief appearance as a Moscow Anchorman in the film Airplane II: The Sequel.

Askin made guest appearances on The Monkees 1967 episode "The Card Carrying Red Shoes", as Nicolai, on Daniel Boone in its 1969 episode "Benvenuto... Who?" as Roquelinm and in the "Fiddler in the House" episode of the 1974 situation comedy Paul Sand in Friends and Lovers as a violin virtuoso. Between 1977 and 1979, he appeared in Steve Allen's PBS series, Meeting of Minds, portraying Martin Luther and Karl Marx. He portrayed a psychology professor in a season six episode of Happy Days. In 1979 he portrayed the character Mr. Hoffmeier of Hoffmeier’s Bakery, judging a pie contest in an episode in the third season of Three’s Company titled, "The Bake-Off".

Askin died in Vienna on June 3, 2005, at the age of 97 and is interred at Zentralfriedhof.

He gained wide recognition and popularity for his recurring role as the stern General Albert Burkhalter in the sitcom Hogan's Heroes appearing in 67 episodes (including the pilot) of the show’s run from 1965 to 1971. Burkhalter was the gruff and rotund German commanding officer of Colonel Klink, the bumbling commandant of a World War II prisoner-of-war camp, manipulated by the American Colonel Hogan so the prisoners would get away with their clandestine activities.