While living in Charlottesville, he got a job at a bar called Miller's. Starting out as a waiter he became friends with a bartender, Dave Matthews.
Griesar was recruited to join the band The Basics, by bassist Houston Ross. LeRoi Moore and Tim Reynolds were also in the group. As a result, he began recording his own music with Matthews. When Matthews quit bartending, they started playing shows at another bar called Eastern Standard.
In August 1990, Miller's hosted practice sessions for Matthews, Moore, Carter Beauford, and Stefan Lessard, while they were closed for late summer cleaning. Before long, he was practising with them.
By 1991, the band (entertaining using the name Dumela) became the Dave Matthews Band, and added violinist Boyd Tinsley, playing at fraternity houses and other bars. During the fall of 1992, as attendance was skyrocketing, the band began planning to cut an album.
Due to the almost constant touring with Dave Matthews Band for 3 years and, owing to his mother's failing health, Griesar left the band. However, after the band's March 23, 1993 show, preferring to play at smaller venues and theatres, as opposed to arenas that the band began to play. He felt that he no longer had a role in the group, unlike Matthews, Tinsley, and Beauford, who had grown into their roles.
Two years later, in 1995, he returned to music, working with artist Lauren Hoffman. In 1996, he joined The Ninth, which included Lessard. The band didn't take off, so Griesar decided to record his own album for his relatives.
In 1998, he assembled Supertanker, and released a solo album, Disposable Love Songs. Two years later, he left the original Supertanker, and released an EP, From the Supertanker Dude with the Zero Obsession. In August 2000, he assembled the second incarnation of Supertanker, which toured briefly.
In 2002 Griesar released a solo album on Offset Records called Superfastgo that also featured performances by DMB saxophonist LeRoi Moore, guitarist Tim Reynolds and pianist Art Wheeler. The album was received well by critics, including a favorable write up in Rolling Stone, and received heavy college airplay. Griesar immediately followed this up with another album called Candyshop released in 2003.