[5] Jarman was 10 years old and in the fifth grade in Nashville when he was discovered in a nationwide talent search by Metro-Goldwyn-Mayer and was cast as Jody Baxter in the film The Yearling (1946), a high-budget film adaptation of the novel by Marjorie Kinnan Rawlings, in which Gregory Peck and Jane Wyman played his parents.

His second film role was in High Barbaree, playing the younger version of Van Johnson's main character.

[10] Jarman is also notable for his starring role as teenager Chick Mallison in the 1949 William Faulkner adaption Intruder in the Dust, which tackled the subject of racism and segregation in the southern states in an unusually open way for a Hollywood film of that time.

Following coursework in pre-law at Vanderbilt, Jarman appeared in Disney's The Great Locomotive Chase (1956), his final movie.

He ran the San Francisco International Film Festival for 15 years (1965–1980) and was known for his in-depth retrospectives of movie stars and directors.

He was executive producer of the music documentary film Fillmore (1972), about rock impresario Bill Graham.