A former United States Air Force officer with the rank of captain, he is best known for winning season four of the reality game show The Amazing Race with his then-partner Chip Arndt, and for his much publicized 2006 relationship with pop singer Lance Bass.

[1] Lehmkuhl was working simultaneously as a physics teacher at Crossroads School for the Arts and Sciences, flight instructor, and model in Los Angeles when he was approached by a casting director for The Amazing Race.

In January 2003, Lehmkuhl competed on the fourth season of the CBS adventure reality show The Amazing Race with his "husband" Chip Arndt.

He published a beefcake calendar for several years and has appeared on sitcoms, soap operas, and other reality television shows.

"[6] Lehmkuhl starred in My Big Gay Italian Wedding, an off-Broadway production from its opening May 5, 2010, in New York City to July 24, 2010.

[9] In July 2006, former NSYNC band member Lance Bass told People that he is gay and in a "very stable relationship" with Lehmkuhl.