Bell subsequently joined Weezer as its rhythm guitarist and backing vocalist, at the request of band member Matt Sharp.

Replacing founding member Jason Cropper, Bell joined the band during the recording of its debut album, Weezer (1994).

Backed by the singles "Buddy Holly", "Undone – The Sweater Song" and "Say It Ain't So", the album was a critical and commercial success.

"[3] Eventually, during his freshman year in high school, Bell's parents allowed him to take guitar lessons from Knoxville musician Ben Bolt.

He worked and started playing in a band with school friends, Tim and Glenn Maloof, named Blooshroom, which Bell described as "Pink Floyd-meets-The Stooges.

[6] In 1991, he became a member of a band named Carnival Art, which released 3 official albums and an EP, with Bell playing bass guitar.

[9] Besides doing back-up vocals and playing rhythm guitar, during Weezer's live performances, Bell takes on many of the multi-instrumental duties, including keyboards or harmonica.

In March 2017, Bell announced that the band's newest album, Clara Obscura (meaning "Clear" and "Obscure"), would be released on April 18.

[14] Bell and Weezer drummer Patrick Wilson collaborated on a cover of the Velvet Underground song "Heroin", for the 2006 film Factory Girl.

During the band's downtime in 2003 and 2004, Bell and his ex-girlfriend Peggy Nunez studied Shakespeare and poetry theory at the collegiate level.

Playing on March 17, 2006 at The Troubador in LA with Weezer tour-mates Ringside,[17] and performing "Our Lips Are Sealed", with the Go-Go's member, Jane Wiedlin, on June 1, 2006 at the Viper Room.

In 2006, Bell made his on-screen debut, playing Lou Reed in the Edie Sedgwick biographical film, Factory Girl.