Philip Loeb was born in Philadelphia on 28th March 1894. He served in the US Army during the First World War. In the early 1920s he joined Theatre Guild in New York City. He worked as an actor on Broadway and eventually appeared in several films including The Mild West (1933), How'd Ya Like That? (1934), Syncopated City (1934), Room Service (1938) and Sweethearts (1938).

Loeb also became active in the Actors Equity Association. He worked closely with Elia Kazan, a member of the American Communist Party. Kazen recalled in his autobiography, Elia Kazan: A Life (1989): "In 1934, when I was in the Party, we helped start a left-wing movement in a very conservative Actors' Equity Association. Our prime goal was to secure rehearsal pay for the working actor and to limit the period when a producer could decide to replace an actor in rehearsal without further financial obligation... I was working on reforming Equity with a fine man named Phil Loeb... Our cause was so just that now, looking back, it's hard to believe there was any opposition to what we were proposing. Still it wasn't an easy to fight to win."

In 1949 he became one of the nation's most popular actors when he appeared as Jake Goldberg in the television series, The Goldbergs. His success was short-lived as his name appeared in Red Channels that was published on 22nd June, 1950. It was claimed he had signed petitions in the 1930s defending the Soviet government and being a member of the Council for Pan-American Democracy, an organization that campaigned against the Jim Crow laws in America. A free copy was sent to those involved in employing people in the entertainment industry. All those people named in the pamphlet were blacklisted until they appeared in front of the House of Un-American Activities Committee (HUAC) and convinced its members they had completely renounced their radical past.

Loeb's problems increased when Elia Kazan and Lee J. Cobb gave information on his radical political activity in the 1930s. Cobb testified that he did not know if Loeb was a former member of the American Communist Party but he accused him of working with Sam Jaffe to control a left-wing caucus in the Actors Equity Association.

General Foods, the sponsors of The Goldbergs, wanted Loeb fired. When Gertrude Berg, the owner of the show, said no, Columbia Broadcasting System (CBS) dropped the show. In 1952, National Broadcasting Company (NBC) agreed to broadcast it but told Berg it had to be without Loeb. This time she gave in and replaced Loeb with Robert H. Harris.

Loeb was now blacklisted and was unable to work. Philip Loeb, depressed by his situation, committed suicide in a New York hotel on 1st September, 1955. His sister commented: "He's been hurt so terribly. Now see what they did to him. They took his living away. They took his life away. A person can only stand so much."