Raised in the suburbs of New Jersey, Mohr headed for New York after high school to pursue a career as a stand-up comic. By the age of 20, he already had ten national stand-up comedy shows under his belt and was commuting between New York and Los Angeles for work. Playing the dimwitted Dorfman, Mohr made his TV series debut as a regular on "Camp Wilder" (ABC, 1992). He returned to New York for "Saturday Night Live", for which he became particularly known for his impersonations of such figures as Tony Bennett and Christopher Walken.

In 1996, Mohr had the recurring role of Jeff's brother on "The Jeff Foxworthy Show" (ABC) before landing a regular slot as a blue-collar guy on the short-lived Fox sitcom "Local Heroes" (Fox). His TV-movie work has been limited to "The Barefoot Executive" (ABC, 1995), although his feature film debut in Jason Alexander's directorial debut "For Better or Worse" (1995) received wider exposure thanks to its airings on TNT—it received a limited regional theatrical release. In 1998 he had a role on the acclaimed Tom Hanks-Steven Spielberg-produced HBO mini-series "From the Earth to the Moon," and followed up with the leading role of the extremely flawed Hollywood film exec Peter Dragon in the harsh, satirical but short-lived sitcom "Action" (1999). A starring role in the TV miniseries adaptation of novelist Dean R. Koontz's "Black River" (2001) followed, and he then served as the titular host for ESPN's first comedy-variety series, "Mohr Sports" (2002), which lasted one season on the cable sports network.

Post-"Jerry Maguire" and "Picture Perfect," Mohr's big screen efforts have been all over the map, ranging from part of the ensemble in the edgy indie "Suicide Kings" (1997) to the human star and voice of the titular parrot in the limp kiddie comedy "Paulie" (1998) to a supporting turn in the action-figures-come-to-life adventure "Small Soldiers" (1998) to the Pacino-esque lead in the Jim Abrahams Mob spoof "Jane Austen's Mafia!" (1998) to the "Scream"-inspired horror thriller "Cherry Falls" (2000). He bolstered his resume with well-acted supporting roles in the dramas "Playing by Heart" (1998), "200 Cigarettes" (1999) and "Go" (1999), rounding it out with a sharp turn as a cynical journalist investigating a related series of Good Samaritan acts in "Pay It Forward" (2000). After that, however, Mohr appeared in a succession of flops and low-profile efforts, including "Speaking of Sex" (2001), the notorious Eddie Murphy bomb "The Adventures of Pluto Nash" (2002) and the uninvolving Hollywood CGI pastiche "S1m0ne" (2002). The actor next appeared opposite Juliane Nicholson in "Seeing Other People" (2004), a comedy about a soon-to-be-married couple whose experimentation with a series of pre-wedding flings wrecks havoc on the their relationships.

Mohr's roots have remained in stand-up comedy and fans of that entertainment form have seen him on such programs as Showtime's "Full Frontal Comedy" and "Evening at the Improv" on the Arts & Entertainment Network (A&E). He would later serve the host of NBC's stand-up talent search reality series "Last Comic Standing" (2003), alongside one of his heroes, talent judge Buddy Hackett, with whom he also starred on "Action." Meanwhile, Mohr showed up in the light-hearted family comedy, “Are We There Yet?” (2005), playing friend and employee to the owner of a sports memorabilia store (Ice Cube). Though panned by many critics, the movie opened number one at the box office. For his next movie, “King’s Ransom” (2005), he played a dimwitted rube who hijacks a millionaire’s plan to kidnap himself by kidnapping him first.