Conan O'Brien mentioned in a 2000 commencement speech that Oxenberg is listed directly ahead of him in the 1986 Harvard yearbook.

Oxenberg dated John Kerry in 1989 after his first marriage ended and before he married Teresa Heinz Kerry. Her first marriage was to the producer Robert Evans, in Beverly Hills, California on July 12, 1998, but the marriage was annulled nine days later.

Oxenberg met actor Casper Van Dien during the filming of the 1999 TV movie The Collectors, and they soon worked together again in the 1999 Evangelical Christian thriller The Omega Code. On May 8, 1999 they married in Las Vegas, Nevada. In 2005 the couple appeared in their own reality series, I Married a Princess, which aired on the Lifetime Television channel in the United States and on LIVINGtv in the United Kingdom. During the 2006-2007 TV season, Oxenberg and Van Dien co-starred in the American drama series Watch Over Me on MyNetworkTV.

Oxenberg is the mother of India Riven Oxenberg