After playing college football for the Nevada Wolf Pack, he was chosen in the seventh round of the 1993 NFL draft by the Dallas Cowboys.

In 1996, he missed 6 games and the playoffs because of a season-ending left scapula injury, finishing with 77 tackles (fifth on the team).

[5] After a CT scan revealed that his left scapula injury had not fully healed and the failure to agree on a restructured contract,[6] the Ravens backed out of the deal two days later on March 20 at a press conference originally intended to announce his signing.

Marion signed as a free agent with the Dolphins in 1998, reuniting with former head coach Jimmy Johnson.

Marion signed with the Detroit Lions in 2004, making 66 tackles, 3 interceptions, and starting 16 games.

He was cut in a salary cap move on April 25, 2005 and was replaced with Terrence Holt as the new starter at free safety.

On February 21, 2024, Marion was hired by the Michigan Panthers of the United Football League as their defensive backs coach.

[9] In 2008, Marion moved to Portland, Oregon where he opened two franchise locations of the National Personal Trainer Institute.

In 2013, Marion became the head coach for the football team at St. John Lutheran High School in Ocala, Florida.