Born in New York City, Harry Carey Jr. was the son of a Judge of Special Sessions who also served as the president of a sewing machine company. He spent his childhood on City Island, New York, and later attended Hamilton Military Academy. Carey turned down an appointment to West Point to pursue his education at New York Law School, where he befriended future New York City mayor James J. Walker.
After a boating accident led to a bout of pneumonia, Carey found solace in writing a play, which he went on to tour the country for three years, earning a significant amount of money. Unfortunately, his next play was a failure, and he lost all of his earnings. Carey's friend, Henry B. Walthall, introduced him to director D.W. Griffith, with whom he would go on to collaborate on many films.
Carey married twice, with his second wife being actress Olive Fuller Golden, also known as Olive Carey. She introduced him to future director John Ford, who would go on to work with Carey on several projects. Carey's influence led Universal Studios head Carl Laemmle to hire Ford as a director, and the two formed a lasting partnership that ended in 1921.
As one of the most popular Western stars of the early motion picture era, Carey occasionally wrote and directed films. In the 1930s, he began to transition into character roles and was nominated for an Oscar for his portrayal of the President of the Senate in Mr. Smith Goes to Washington (1939). Carey also worked with Ford again in The Prisoner of Shark Island (1936) and appeared alongside his son, Harry Carey Jr., in Howard Hawks's Red River (1948).
Carey's later years were marked by a struggle with emphysema and cancer. He passed away after a long illness, and John Ford dedicated his remake of 3 Godfathers (1948) to him, saying "To Harry Carey--Bright Star Of The Early Western Sky."