He was born in Winnipeg, and his father, Ferdie Peterson[2] (who was also a drummer) got him to start playing the drums at age two, and professionally when he was four years old.

[5] Garry was a child prodigy drummer, and backed Lionel Hampton, The Four Lands, Ames Brothers, and The Andrews Sisters.

When The Guess Who stopped in 1975, and Garry formed an unsuccessful band with Mandala lead singer Roy Kenner called Delphia.

[12] He then stepped away from a music for a few years, working jobs including as a night clerk in his Father in law's hotel and as an insurance salesman.

[16] Peterson’s booting from BTO was an especially dark time for him, as he sold his home and art collections to pay for taxes[2] since he was receiving no income, and Burton Cummings never forgave him for ditching him to go with Bachman.

[16] A year after leaving Bachman–Turner Overdrive, he joined a separate unauthorized band formed by Jim Kale calling themselves The Guess Who.

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.

[19] As a result of a court agreement, Peterson’s Guess Who could not perform songs written or co-written by Cummings or Bachman.

[21] Born in Canada, Garry now lives in the United States, Greensboro, North Carolina, with his wife Kimberly Ann Peterson.