Maren Jensen was born in Glendale, California. Her father was a physician, and her mother was a secretary with the Los Angeles Zoo. She is a middle child, with an older brother, Dana, and a younger sister, Kathleen. Maren attended Herbert Hoover High School from 1971 to 1974, and after graduating received a scholarship to attend UCLA, where she majored in Theater Arts and Law.

While still in college, Maren began a modeling career. She was featured on the covers of Vogue and Mademoiselle. A mutual friend introduced her to the agent Barbara Gale, who helped arrange two network commercials and a role in The Hardy Boys/Nancy Drew Mysteries in 1977. In 1978, Jensen starred in Battlestar Galactica. She was featured on the cover of TV Guide in April 1978. Her last known role was in Wes Craven's 1981 horror film Deadly Blessing alongside Sharon Stone. Her career was cut short by illness, after she contracted Epstein-Barr Syndrome.

Jensen was a longtime companion of singer-songwriter Don Henley. In 1982, Henley released his first solo album, I Can't Stand Still, and dedicated it to her. She is credited for "Harmony Vocals" on the song "Johnny Can't Read," and is credited in the liner notes for having composed the piano intro and interlude on the song "A Month of Sundays" on Henley's 1984 album Building the Perfect Beast. She appeared in the video for Henley's song "Not Enough Love In the World" in 1985. Henley and Jensen were engaged, but they separated in 1986. Jensen helped Henley establish The Walden Woods Project in the early 1990s, an organization dedicated to protecting the Walden Woods area in Concord, Massachusetts from development.