Peterson performed congas, drums and other percussive instrument on Randy Bachman's solo album Axe in 1970.[10] Peterson, Cummings and Bill Wallace all played on Rick Neufeld's 1974 album Prairie Dog. Between 1981–1982, he played drums on albums for Richard Stepp, Herman van Veen, and Nancy Nash.
The Guess Who stopped in 1975, and Garry formed an unsuccessful band with Roy Kenner called Delphia.[11] He later worked jobs in a hotel and as an insurance salesman.[12] He backed Burton Cummings for a while, until 1983, when he decided to leave Cummings to join Bachman–Turner Overdrive.[7] Peterson plays on their 1984 Bachman–Turner Overdrive album. Although he was not a member at the time, Garry played percussion, drums and backing vocals on BTO's first album, also called Bachman–Turner Overdrive from 1973.[13]
Garry was kicked off of the bands tour after breaking his ankle in an Ice hockey accident.[14] Garry had received a phone call from Tim Bachman saying that the band “no longer required” him.[14] Peterson’s booting from BTO was an especially dark time for him, as he lost his house since he was receiving no income, and Burton Cummings never forgave him for ditching him to go with Bachman.[14]
A year after leaving Bachman–Turner Overdrive, he went back to The Guess Who. Since then, he had toured with Kale, but was the sole original member in the Guess Who from Kale retiring in 2016 until the Guess Who ended in September 2024. The last time all four original Guess Who members performed together at the closing ceremonies of the Pan American Games at Winnipeg Stadium on August 8, 1999.[15] A 2003 performance at the Molson Canadian Rocks for TorontoSARSbenefit concert with a capacity of 450,000 is now recognised at the largest outdoor ticketed event in Canadian history.[16]
From 2023 onward, Bachman and Burton Cummings have been getting into legal battles with the new Guess Who featuring Garry Peterson. These battles include a Cease and desist and accusations of false advertising.[17] As a result of a court agreement, as of April 2024, Peterson’s Guess Who can not perform songs written or co-written by Cummings or Bachman. Garry was the only original Guess Who member touring with the new version currently from 2016, but in recent years was on occasion absent from concerts because of health reasons, causing those gigs to contain no original members on stage, with the oldest serving member in the band on stage only dating back to 2008.[17] The U.S. Patent and Trademark Office records show that since 2006, Peterson and Kale co-own the rights to the "Guess Who" name only during live performances and not for studio releases.[18]
Burton Cummings and Randy Bachman won the long running Guess Who lawsuit in September 2024, ended Garry's Guess Who group.[19]
Born in Canada, Garry now lives in the United States, Greensboro, North Carolina, with his wife Kimberly Ann Peterson.[20] He and Kimberly met at the Greensboro Coliseum Complex when Bachman-Turner Overdrive were playing there.[7] Peterson has dual citizenship of Canada and the United States.[6] He has leg problems, and sometimes uses a wheelchair or a mobility scooter when having to walk long distances.[4]