Sommer grew up in the San Francisco area where he played youth hockey for Skyline High School before moving to Calgary at age 17.

[2] On November 1, 2009, while with the Worcester Sharks, Sommer became just the fourth head coach in AHL history to reach 400 wins.

[3] On February 10, 2016, while with the San Jose Barracuda, Sommer became the winningest head coach in AHL history when he reached 637 wins.

[8] On July 12, 2022, shortly after Mike Grier was hired to replace Doug Wilson as the Sharks GM, Sommer was named head coach of the San Diego Gulls.

[9][10] On April 15, 2023, Roy Sommer announced his intention to retire on the day of the Gulls' final game of the season against the Colorado Eagles.