[7] Cummings was born and raised in Winnipeg by his mother and maternal grandparents, after his father left the family during his infancy.

[11] In 1964 Cummings joined local R&B band the Deverons (not to be confused with an American group called the Devrons) on piano and vocals.

[12] In early 1966, shortly after his 18th birthday, Cummings joined another regionally successful band, Chad Allan & The Expressions, to replace departed keyboardist Bob Ashley.

[14] This group had been subjected to a record company publicity stunt in which their 1965 hit single "Shakin' All Over" was released anonymously with the message "Guess Who?"

", forcing the group to accept the nickname; their latest releases had been issued under the name Chad Allan & The Expressions with "Guess Who?"

[26] Due to a dispute with his record label, his 1980 album Woman Love was not released in the United States but was another substantial hit in Canada that earned Cummings another Juno Award.

[28] Cummings joined a short reunion tour of the classic Guess Who lineup in 1983,[29] which resulted in the live album Together Again!

[20]After an extended break from recording, Cummings released the live album Up Close and Alone in 1997, featuring songs from throughout his career performed on solo piano.

In July 2003 the group performed before an estimated audience of 450,000 at the Molson Canadian Rocks for Toronto SARS benefit concert.

[33] In 2006, Cummings and Randy Bachman started a new duo project backed by the Canadian rock band The Carpet Frogs, but were unable to use the name The Guess Who, which had been trademarked by bassist Jim Kale.

[45][46] On December 30, 2009, Cummings was named an officer of the Order of Canada by Governor General Michaëlle Jean, to mark a lifetime of outstanding achievement, dedication to community, and service to the nation.

[53] In May 2018, Cummings was involved in a serious car crash in Los Angeles that required physical and mental therapy and the cancellation of several weeks of performances.