Lovejoy was first married to Frances Williams (1901–59), but divorced in the late 1930s. In 1940, Lovejoy married Actress Joan Banks (1918–1998), with whom he had a son and a daughter.
A successful radio actor, Lovejoy played Broadway Harry on the Gay Nineties Revue and was heard on the 1930s crime drama series Gang Busters. Lovejoy was a narrator (during the first season) for the show This Is Your FBI.
In films of the 1940s and 1950s, Lovejoy mostly played supporting roles. Appearing in movies such as Goodbye, My Fancy (1951) with Joan Crawford, and The Hitch-Hiker (1953) directed by Ida Lupino, Lovejoy was effective playing the movie's everyman in extraordinary situations. He was in several war movies, notably Stanley Kramer's Home of the Brave (1949), Breakthrough (1950), Joseph H. Lewis's Retreat, Hell! (1952) which portrayed the United States Marine Corps' retreat from the Chosin Reservoir (Changjin Reservoir) during the Korean War and as a Marine sergeant again in Beachhead (1954). In 1951, he had the title role in I Was a Communist for the FBI with co-stars Ron Hagerthy, Paul Picerni, and Philip Carey.
On October 2, 1962, Frank Lovejoy died of a heart attack in his sleep at his residence in New York City. His wife, Joan Banks, called for medical help after she was unable to wake him. The couple had been appearing in a New Jersey production of the Gore Vidal play The Best Man.
