Born in Harrisburg, Pennsylvania, he graduated from Sarah Lawrence College in Bronxville, New York, with a degree in cinema studies.

Mabius wed Ivy Sherman, an interior designer, in January 2006; the two first met in high school during a health education class.

Mabius was arrested in Nassau County, Florida, on February 20, 2025, and charged with battery and resisting law enforcement without violence.

[9] Mabius also appeared in the 2006 Lifetime original film A Christmas Wedding, and had a leading role in the 2011 British science-fiction drama series Outcasts.

[12] Mabius competed as a luger in the late 1980s and was named an honorary captain for the U.S. luge team for the 2010 Winter Olympics along with astronaut Scott Parazynski.