Dean Jagger has a star on the Hollywood Walk of Fame at 1523 Vine Street for his contribution to motion pictures.

Jagger studied acting at Chicago's Lyceum Arts Conservatory. He joined a stock company as Spencer Tracy's replacement. He performed in vaudeville, on the radio and on stage, making his Broadway debut in 1925 in a bit part in a George M. Cohan production. Through the 1930s and 1940s, he performed in a number of Broadway plays, including the original production of Tobacco Road.

Jagger made his film debut in The Woman from Hell (1929) with Mary Astor. He became a successful character actor and appeared in almost 100 films in a career that lasted until shortly before his death. Jagger made his breakthrough with his portrayal of Brigham Young in Brigham Young (1940). According to George D. Pyper, a technical consultant on the film who had personally known Brigham Young, Jagger not only resembled Young, he also spoke like him and had many of his mannerisms. Thirty-two years later, in 1972 he was baptized a member of the Church of Jesus Christ of Latter-day Saints.

When Jagger tried to marry his second wife, Gloria Ling, in 1947, they were denied a marriage license in California due to a state law "forbidding unions between Caucasians and Mongolians [sic]"; Ling's father was born in China.

He received an Academy Award for Best Supporting Actor for his role in Twelve O'Clock High (1949). In the film, he played the retread World War I veteran, middle-aged adjutant Major/Lt. Col. Harvey Stovall, who acts as an advisor to the commander, General Savage (Gregory Peck). He appeared in the biblical epic The Robe (1953) as the weaver Justus of Cana. He played the retired Army major general Tom Waverly honored by Bob Wallace (Bing Crosby) and Phil Davis (Danny Kaye) in the musical White Christmas (1954), and an impotent local sheriff in the modern Western Bad Day at Black Rock (1955), starring Spencer Tracy. Jagger also portrayed the father of Elvis Presley's character in 1958's King Creole. He was the traveling manager for an evangelist played by Jean Simmons in the acclaimed 1960 drama Elmer Gantry.

For the 1956 British science-fiction film X the Unknown, Jagger refused to work with Director Joseph Losey because Losey was on the Hollywood blacklist. Losey was removed from the project after a few days of shooting and replaced with Leslie Norman.

Jagger also achieved success in the television series Mr. Novak, receiving Emmy Award nominations for his role in 1964 and 1965, as well as the California Teachers Association's Communications Award, along with star James Franciscus, in 1963 for his portrayal of high school principal Albert Vane. However, even before he left the show to have a major medical operation, he was less than happy with the series, clashing repeatedly with the Writers and Directors and describing "the Mr. Novak company" afterwards as "a mishmash of unbelievable amateurishness."

In 1971, Jagger appeared on The Partridge Family. He played a prospector named Charlie in the Christmas episode "Don't Bring Your Guns to Town, Santa". He won a Daytime Emmy award for a guest appearance in the religious series This Is the Life. He played dozens of TV dramatic roles, including an episode of The Twilight Zone called "Static." In an early episode of the television series Kung Fu, Jagger appeared as Caine's grandfather, who wants little to do with him, but starts Caine on his series-long search for his half-brother Danny.