Prior to turning professional, Toews attended Quinnipiac University, where he was named to the All-ECAC Hockey Second Team.

[3] He joined the major-midget team the Fraser Valley Bruins with Mackenzie Skapski and they both suffered injuries as a result of a bus accident on December 11, 2009.

[2] Despite this, Toews returned to the Fraser Valley Bruins, where he experienced a growth spurt, and led all BC Hockey Major Midget League defencemen with 37 points in 39 games during the 2010–11 season.

In his first season, he was named to the 2011–12 BCHL All-Rookie Team,[4] and was offered a full hockey scholarship to play at Quinnipiac University.

[3] However, Toews returned to the Eagles for the 2012–13 season, where he won the 2013 BCHL Championship and the Western Canada Cup in Nanaimo.

He played in the ECAC Hockey quarterfinals against Union College, where his two late period assists helped send Game One to triple overtime, which the Bobcats won.

[16] On April 15, 2016, Toews opted to conclude his collegiate career and signed a three-year, entry-level contract with the New York Islanders.

[20] Prior to the 2017–18 season, Toews attended the Islanders training camp where he competed against Adam Pelech, Scott Mayfield, and Ryan Pulock for a spot on the final roster.

[23] On December 19, 2018, Toews earned his first NHL recall after he had recorded 19 points in 24 games, which ranked second amongst Sound Tiger defencemen.

[29] The team then faced the Carolina Hurricanes in the second round where Toews subsequently recorded his first career playoff goal on May 1, 2019.

[30] Following their elimination, Toews trained at Quinnipiac University and in Vancouver with NHL veterans Morgan Rielly and Shea Theodore.

[31] As a restricted free agent with the Islanders, due to salary cap constraints, Toews was traded by New York to the Colorado Avalanche in exchange for 2021 and 2022 second-round draft picks, on October 12, 2020.

Toews's parents were baseball fans who named their sons after Toronto Blue Jays fielder Devon White and Texas Rangers pitcher Nolan Ryan.