Doucette's film debut, in an uncredited role as a reporter, in Footsteps in the Dark in 1941. He appeared uncredited in at least two other movies before his budding film career was interrupted by his military Service during World War II. Following his discharge, he resumed acting in Hollywood, where he soon began to receive more substantial, credited roles in releases by smaller production companies, such as The Burning Cross and The Road to the Big House for Somerset Pictures Corporation in 1947. Doucette continued to progress in obtaining dramatic roles for larger studios, including a small part as an Architect in The Fountainhead in 1949 and in the 1970 epic Patton when he portrays 3rd Infantry Division Commander Major General Lucian K. Truscott. His other notable performances include bit parts in High Noon, The Robe, Sierra, and the mega-budget Cleopatra. More familiarly, Doucette also appears in the John Wayne films The Sea Chase, The Sons of Katie Elder, True Grit, and Big Jake.