John Petrucci was born on July 12, 1967, in Kings Park, New York, to an Italian American family. He picked up the guitar at the age of eight because his older sister was allowed to go to bed later in order to practice the piano. However, he decided to quit the guitar when his attempts to stay up late were unsuccessful. He picked up the guitar again at the age of 12. Petrucci has said he committed to practicing guitar 6 hours a day when he discovered it was his passion. His early influences were bands like Led Zeppelin, Black Sabbath, AC/DC, and later developed an interest in progressive rock and heavy metal, exemplified by Rush, Yes, Iron Maiden, Dixie Dregs and Metallica.
Eventually, his childhood friend and future Dream Theater keyboardist Kevin Moore invited Petrucci to join his cover band. Petrucci attended Berklee College of Music in Boston with childhood friend John Myung (bass), where they met future bandmate Mike Portnoy (drums). While in Berklee they often covered two of their biggest influences, Iron Maiden and Rush. These three, in addition to Kevin Moore, formed the band Majesty. Because there was already another band with the same name, the group later became Dream Theater.
While Petrucci is most commonly associated with Dream Theater, he is also in the project band Liquid Tension Experiment, and has appeared as a guest on records by other artists, such as the Age of Impact album by the Explorer's Club.
Petrucci has released a guitar instructional video, Rock Discipline, which covers warm-up exercises, exercises to avoid injury while playing, alternate picking, sweep picking, chords and other techniques for developing one's guitar playing. Petrucci also has a book named "Guitar World presents John Petrucci's Wild Stringdom", which was compiled from columns he wrote for Guitar World magazine under that title.
In 2001, Joe Satriani and Steve Vai invited Petrucci to tour with them on the popular G3 guitar tour, which exposed him to a massive number of new fans and inspired a solo album. The album, Suspended Animation, was released on March 1, 2005, and was available for order from his web site. Petrucci also appeared on the 2005 and 2006 G3 tours, and in 2007, went on G3 tour again, this time with Paul Gilbert and Joe Satriani. In a recent video with Larry DiMarzio, Petrucci announced that he is working on a follow up to his 2004 album, Suspended Animation and a new Dream Theater album.
Petrucci also wrote and recorded two instrumental soundtrack songs for a Sega Saturn game titled Digital Pinball: Necronomicon. Each track is roughly two minutes long, and are named simply Prologue and Epilogue. In a spoof rock band, Nightmare Cinema (which was the Dream Theater members changing instruments for a gig), he used the "alternate stage name" Johnny James.
In 2012, Petrucci was invited once again to join Joe Satriani on the G3 tour, along with Steve Morse. He was accompanied by bassist Dave LaRue and drummer and Dream Theater bandmate Mike Mangini.
Dream Theater bandmate Jordan Rudess revealed in an interview that Petrucci is a practicing Catholic. He currently lives in St. James, New York, with his wife Rena Sands, a guitarist in the all-female heavy metal band Meanstreak, and they have three children—twins Samantha and Renato, and Kiara. He is the uncle of Jake Bowen, a guitarist in the progressive metal band Periphery. He is also an avid fan of bodybuilding and dedicates much of his off time to weight training. He is a voting member of NARAS.