In 2012, through his website, Armstrong started releasing music that influenced him, along with stripped-down cover songs of his own under the name Tim Timebomb.

[2] They grew up a few blocks apart in Albany, California, where Armstrong lived with his mother, father, and older brother, Jeff.

[3] Armstrong's relationship with Bikini Kill drummer Tobi Vail inspired the Rancid song "Olympia, WA" from ...And Out Come the Wolves.

[8] Some of Rancid's songs on 1998's Life Won't Wait ("Who Would've Thought", "Corazón de Oro") detail Armstrong and Dalle's relationship, and songs on 2003's Indestructible ("Fall Back Down", "Ghost Band", "Tropical London") deal with Armstrong's feelings about his divorce.

[9][10] Armstrong's cousin, Scott, was the guitarist for Canadian punk band Desperate Minds, but they did not know each other until they were introduced at a show in Chicago in 1988 by John Jughead of Screeching Weasel.

In 1987, along with singer Jesse Michaels, bassist Matt Freeman and drummer Dave Mello, Armstrong formed the ska punk band Operation Ivy and enjoyed modest success before the group disbanded in 1989, the same night the album was released.

The first line-up featured Armstrong on vocals and Freeman on guitar, as well as drummer Erik Larsen, keyboardist Joey Schaaf, vocalist Andrew Champion, guitarist Grant McIntire, and bassist Joel Wing.

It disbanded when Freeman joined MDC on bass while Armstrong was a roadie for the band, while Pat and Dave went on to form Schlong.

[16] During this time, Freeman suggested the two start a new band together, partially in hopes of curbing Armstrong's alcohol addiction.

They formed the group Transplants with drummer Travis Barker, of Blink-182, and released their self-titled debut album on October 22, 2002.

They played their first show since 2006 on Conan to promote Barker's new solo album, on which the song "Saturday Night" is featured.

[citation needed] In 2007, he released his first solo album entitled A Poet's Life with the Aggrolites as his backing band.

The track from that album "Into Action" was reported as the number one most played and requested in 2007 on then XM Satellite Radio channel Fungus 53.

[18] In March 2023, Armstrong announced the formation of a new band called Bad Optix that featured his former Operation Ivy bandmate Jesse Michaels, Circle Jerks drummer Joey Castillo and Trash Talk bassist Spencer Pollard.

He and Matt Freeman also play in a psychobilly band called Devils Brigade, and he co-produced their debut album.

And in 2012, Armstrong wrote and performed on Joe Walsh's song "Hi-Roller Baby" from his solo album Analog Man.

[26] Armstrong also co-produced the EP Footprints and Broken Branches in 2019 by the Los Angeles-based country musician Rosy Nolan along with Kenny Feinstein of the band Water Tower.

The single cutaway hollowbody electric guitar featured a 17" wide body in a flat-black urethane finish, parallel tone bars and sound post, two "Black Top" Filter'Tron pickups, Grover tuners, big block fretboard inlays, a harp tailpiece and gold-plated hardware.

[30] Armstrong's signature model is based on his 1971 Baldwin-era Gretsch Country Club which he spray-painted black and flipped to accommodate his left-handed playing.