Billy Sheehan's first electric bass was a Hagström FB, which was soon sistered by a Precision bass similar to Tim Bogert's. After acquiring the Precision bass, he removed the frets from the Hagström. Over the years, he heavily modified the Precision bass as well, adding a neck pickup and additional support for the bolt-on neck, which Sheehan considers its greatest weakness. The neck pickup was added for what Sheehan referred to as "super deep low end" modelled after Paul Samwell-Smith of the Yardbirds. The Gibson EB-0 type pickup in the neck and the original split Precision bass pickup each have their own separate output jacks on the bass itself, allowing for control of the tone via the bass. Sheehan also uses two amps to achieve his signature tone (as do Chris Squire of Yes and Doug/Dug Pinnick of King's X), one with full distortion and notch filtering to sound more guitar-like for solos, and one super clean for the low end of the neck pickup. This bass has been retired, but he affectionately refers to it as "The Wife".
Sheehan regularly played "The Wife" until the late 1980s when he began using self-designed Yamaha Attitude basses. These instruments are modelled on his Precision, but feature, in Sheehan's estimation, a number of improvements, including multi bolt-on neck construction style and an aftermarket device called the Hipshot D-tuner on the E-string, which allows him to quickly drop the pitch of the string to D and raise it again.
Sheehan's main bass is a Yamaha Billy Sheehan Attitude 4 string bass with aftermarket blue LEDs and laser pointer, by Sims UK. He is a long time user of the Hipshot Bass D-tuner which allows him to drop the low E to a lower D on his bass' 4th string; all of his signature Yamaha basses have them factory installed. Sheehan is a long time Ampeg user, he has used Ampeg SVT-4Pro amplifiers for several years. Ampeg also makes his signature SVP-BSP pre-amps.
Sheehan cites a variety of influences, from Tim Bogert to Johann Sebastian Bach, but credits Jimi Hendrix as his primary influence, possibly because his first show was a Hendrix concert. He also claims to have gotten the idea for two-handed tapping from Billy Gibbons of ZZ Top, who he saw use his right hand index finger to tap a note on the fretboard of his guitar at a concert.
Sheehan’s first full-time band was Talas, a power trio with Dave Constantino on guitar and Paul Varga on drums. The band played a mixture of cover songs and original material, and all three instrumentalists alternated on lead vocals. In 1978, Talas released their eponymous debut album, which generated the regional hit single, "See Saw". It was during this time that Sheehan wrote some of his most famous songs, "Shy Boy" (later re-recorded with David Lee Roth), and "Addicted to that Rush" (later re-recorded with Mr. Big).
In the late 1970s, Sheehan also played in a band called Light Years with drummer Ron Rocco who had earlier played in a band called Black Sheep with Foreigner singer Lou Gramm in Rochester, NY. After Sheehan returned to Talas they opened a show for UFO in Buffalo. This led Sheehan to an association with guitarist Michael Schenker and also helped land him the job touring with UFO in 1983. Talas independently released their debut eponymous "Talas" LP on Evenfall Records (reissued by Metal Blade) and then "Sink Your Teeth Into That" on Relativity Records.This lineup garnered Talas' first national exposure in 1980, when they opened thirty shows for Van Halen. However, success was elusive, and even as their brand of what came to be known as "glam metal" gained popularity over the next few years, Talas remained an unsigned act, due largely to poor management.
Seeking to take Talas further than just regional success, Sheehan reformed Talas with another drummer (Mark Miller), guitarist (Mitch Perry, also later of Heaven), and vocalist, Phil Naro, who, coincidentally, had replaced Lou Gramm in Black Sheep. Naro also worked with Sheehan's late 1970s side project, the Billy Sheehan Band. Talas would release only one more album, Live Speed on Ice. After Mitch Perry left the band, he was replaced by Johnny Angel, who played guitar with them for their 1985/86 US tour opening for Yngwie Malmsteen's Rising Force. There was a fourth Talas record, tentatively titled "Lights, Camera, Action" to be issued on Gold Mountain/A&M, but it never got past the demo stage due to Sheehan leaving to join David Lee Roth's solo band. Talas did briefly continue on under Phil Naro sans Sheehan, enlisting Jimmy Degrasso on drums, Al Pitrelli on guitar and Bruno Ravel on bass, but by this time Talas was dead. Sheehan also briefly played for Max Webster, a Toronto based rock band fronted by Kim Mitchell, prior to joining Roth's band.
In the early 1980s, Sheehan became involved with the proto-thrash metal band Thrasher, during this time he shared the stage with future Anthrax guitarist Dan Spitz. His involvement with Thrasher did not last long, but he did play on two songs from the self titled LP, which has not been released on CD to date. Sheehan has recently reunited the original Talas trio for a few shows here and there as well as the live CD If We Only Knew Then, issued on Metal Blade. ("Sink Your Teeth Into That" and "Live Speed On Ice" were combined and re-released as the CD Billy Sheehan: The Talas Years on Relativity Records.) On 2006 December 23, Sheehan sat in with the Dave Constantino Band at Club Infinity in Buffalo. Johnny Angel was the solo opening act for the evening. On February 10, Billy Sheehan attended an Anti-Scientology picket answering questions regarding his allegiance to Scientology.
David Lee Roth tapped Sheehan, guitarist Steve Vai, and drummer Gregg Bissonette to be his band for the Eat 'Em and Smile album, Roth's first full studio release, following the modestly successful four song release "Crazy From the Heat", after leaving Van Halen. After Roth's Skyscraper album was issued, Sheehan left the band to pursue other opportunities. Steve Vai followed after the tour ended. After that he tried to make a project with Steve Stevens (ex-Billy Idol) but it didn't work. In 1988, Sheehan, along with singer Eric Martin, guitarist Paul Gilbert, and drummer Pat Torpey formed Mr Big. Mr Big had two American hits with "Addicted to That Rush" from their eponymous first album and the ballad, "To Be With You" (from their second album, Lean Into It,) but were unable to duplicate it with later releases. However, the band had a dedicated following in Japan. Internal tensions led to Gilbert quitting the band in 1997. Richie Kotzen replaced him, and was with Mr Big until the group's breakup in 2002. Sheehan has toured Poland with UFO.
Sheehan has performed on many of Steve Vai's solo albums and was the bassist for Vai's touring band from 2001 until early 2007, an incarnation which Vai dubbed "The Breed". The Breed was noted by Vai as having "worked beyond his expectations" and has expressed that he hopes to work with Sheehan and The Breed in the future as schedules permit. In 1999, he helped to record the album "Brotherhood", with the multi-platinum Japanese band, B'z, and subsequently played with the band live for their 2002 "Green" Tour in front of total 750,000 audience. In 2001, Sheehan released a long-awaited solo album, Compression, and in 2005, he recorded his second solo effort, Cosmic Troubadour. Both feature Sheehan singing and playing guitar.
In 2002, Sheehan guested on metal fusion band Planet X's MoonBabies, which led to his involvement on Planet X keyboardist Derek Sherinian's solo album Black Utopia 2003. Another of Sheehan's projects is the three-piece jazz-rock-fusion band, Niacin, which also features drummer Dennis Chambers and Hammond B3 player John Novello. Sheehan is also the author of a popular series of instructional books and videos, and, even though he has little formal training on the electric bass guitar, gives bass clinics and has hosted seminars at the famous Berklee College of Music. Sheehan along with Mike Portnoy, Gary Cherone, and Paul Gilbert performed three concerts in the end of May 2006 as Amazing Journey: A Tribute to The Who. Sheehan recently joined up with bassists Jeff Berlin and Stu Hamm, along with guitarist Jude Gold and drummer John Mader for the bx3 tour; a spin off of the G3 tour focusing on bass instead of guitar. They recently completed a short Southeast Asian tour, stopping in Bangkok, Hong Kong and Taipei.
Billy Sheehan formed Niacin as an outlet for his jazz fusion and prog rock inclinations during the mid-'90s. The trio also featured keyboardist John Novello and drummer Dennis Chambers, both musicians who had crossed frequently between the worlds of jazz and rock during their careers. With Niacin, Novello devoted himself especially to the Hammond B-3 organ, a longtime mainstay of both jazz and prog rock. The band recorded a self-titled debut album in 1996, following it up in 1998 with High Bias. An import-only concert recording, Live!: Blood, Sweat and Beers, surfaced later that year as well. For their next album, Niacin moved from Stretch to Magna Carta, the label that became virtually synonymous with technique-oriented neo-prog rock at the turn of the millennium. Deep was released in 2000 and featured the group's first vocal track, courtesy of special guest Glenn Hughes (Deep Purple), as well as Toto guitarist and session ace Steve Lukather. Time Church released in 2001.
In January 2009 Billy Sheehan reunited with his old Mr Big band members: Eric Martin, Paul Gilbert and Pat Torpey for a reunion tour in Japan. In April 2009 Sheehan's third solo album, Holy Cow!, was released by Mascot Records. The album features guest appearances from Paul Gilbert, ZZ Top's Billy Gibbons and King's X bassist Dug Pinnick. Gilbert has stated in an interview that his amicable collaboration with Billy on Holy Cow!, recorded prior to January, was likely a factor in the decision to reunite Mr Big.
In October-November 2009 he went on an eighteen date clinic tour incluing Australia with fellow virtuoso bassist, Dionald Tubang.