Growing up in Northern California, Grant Show developed an interest in acting while he was still in high school. He pursued his passion to UCLA, where he studied theater arts for a year before leaving school to appear on the TV show Ryan's Hope. Other appearances would follow on shows like The Love Boat, but Show didn't give up on studying his craft at the first sign of a blossoming career. He also traveled to London, where he enrolled at the London Academy of Music and Dramatic Art for a year.

In 1992, Show joined the cast of a new night-time soap called Melrose Place, premiering on the Fox network. The show became a massive hit, and thousands of viewers came to know Show for his hunky character, Jake Hanson. He stayed with the show until 1997, and he went on play prominent roles in the cult hit Point Pleasant and 2007's The Girl Next Door. He also took a recurring role as Jack Dawson on the saucy series Dirt with Courteney Cox Arquette. The next year, Show appeared in the regular role Tom Decker in the '70s period drama series Swingtown. He went on to appear in Justice for Natalie Holloway, Born 2 Race, and the 2012 horror film The Possession. In 2013, Show returned to television in Lifetime series Devious Maids.