Johnson won the silver medal at the novice level of the 1974 U.S. Figure Skating Championships. She gave up competitive skating in 1977 to turn professional and join the Ice Capades, and subsequently began an acting career, making her film debut in Ice Castles, in which she portrayed Alexis "Lexie" Winston, a figure skater who is blinded by a blood clot in her brain. The film, a romantic drama co-starring Robby Benson, was a minor success in December 1978, grossing $18 million in the US. Johnson, who was described as "an appealing young woman who actually happens to be a good skater who can act" by film critic Roger Ebert, was nominated for a Golden Globe as "New Star of the Year in a Motion Picture – Female" for her performance in the film.

Johnson was subsequently cast in the lead role of the Disney horror drama, The Watcher in the Woods. The film received a limited release in April 1980, but was soon withdrawn and not given a wider release until October 1981. Also in 1981, Johnson starred as Bond girl Bibi Dahl in the James Bond movie For Your Eyes Only. In that movie she played yet another ice-skater who attempts to seduce an unwilling and much older James Bond, played by Roger Moore. In 1984, Johnson starred in Where the Boys Are, a remake of the 1960 film of the same name. The film was a critical and box-office failure.

In 1996, Johnson quit acting to concentrate on her family; her last acting role at that time was a made-for-television film, Fugitive X: Innocent Target.

In 2007, she returned to acting in a community theater production of It's a Wonderful Life.

Johnson currently lives in the Los Angeles, California area with her husband and their two children, son Kellen and daughter Jensie. In January 2010, she suffered a stroke brought on by a patent foramen ovale, a heart condition, and subsequently underwent heart surgery.