Before his acting career, he was the lead singer of the 1960s rock group Clear Light, which played the same concerts with acts such as The Doors, Jimi Hendrix, and Janis Joplin. After the band broke up, he starred in the Broadway production of Hair and the Tony Award-winning Sticks and Bones. After four years in New York, he moved back to California to star in the television film Sunshine (1973), about a young mother dying of cancer, and featuring the songs of John Denver. There was also a short-lived television series based on the film. The song "My Sweet Lady" from the film reached #17 on the Billboard Hot 100 Pop Chart in 1974. Sunshine Christmas, a sequel, was produced in 1977.
DeYoung was born in Los Angeles. He is a 1968 graduate of California State University, Los Angeles.
Since then, DeYoung has appeared in more than 80 films and television series, including Harry and Tonto (1974), The Lindbergh Kidnapping Case (1976), Captains and the Kings (1976), The 3,000 Mile Chase (1977), Centennial (1978) as John Skimmerhorn, Blue Collar (1978) as an FBI agent, Shock Treatment, the 1981 sequel to The Rocky Horror Picture Show, where he played twin characters who sang a duet with each other, Master of the Game (1984) as Brad Rogers, and Flight of the Navigator (1986) in which he played Bill, David's father. Also in the 1980s, he made a guest appearance on Murder, She Wrote, like fellow Navigator actor Joey Cramer. In 1987 he guest-starred in the television show Beauty and the Beast as the specialist in voodoo Professor Alexander Ross. In the 1989 Civil War film Glory, he played Union Colonel James Montgomery. Other projects included the films Suicide Kings (1997) and Last FLIGHT Out (2004).
He has guest-starred on Star Trek: Deep Space Nine (in the episode "Vortex"); as reporter Chuck DePalma in four episodes of JAG; Rep. Kimball in the episode "The Day Before" on The West Wing; and as John Bonacheck, Amber Ashby's kidnapper, on The Young and the Restless in 2007.
In 2010, DeYoung appeared in Monte Hellman's independent romantic thriller Road to Nowhere.
In the 2014 film Wild he played Ed, a summer resident of the Kennedy Meadows Campground on the Pacific Crest Trail.
