Girard, a small, skilled defenseman, became a big part of the present and future of the Colorado Avalanche when he was acquired from the Nashville Predators on Nov. 5, 2017, in a three-team trade that also included the Ottawa Senators and involved forwards Matt Duchene and Kyle Turris. Girard, a second-round pick (No. 47) by Nashville in the 2016 NHL Draft, played the rest of the 2017-18 season for the Avalanche, finishing with 20 points (three goals, 17 assists) in 68 games and helping Colorado earn the second wild card into the Stanley Cup Playoffs from the Western Conference one season after finishing last in the NHL (22-56-4).

Girard skated for the Avalanche during the 2022 playoffs and got his name on the Stanley Cup despite leaving Game 3 of the Western Conference Second Round with an injury and missing the rest of Colorado's run to the Stanley Cup. He had 28 points (five goals, 23 assists) in 67 regular-season games and set NHL career highs in points (37), goals (six) and assists (31) in 76 games the following season.

Girard was traded to the Pittsburgh Penguins on Feb. 24, 2026. He had 24 points (three goals, 21 assists) the prior season, his seventh with at least 20 points that tied Erik Johnson and John-Michael Liles for most by a defenseman in Avalanche/Quebec Nordiques history.

Prior to turning pro, Girard played three seasons with Shawinigan of the Quebec Major Junior Hockey League, where he earned league-wide honors in each of his three seasons including Defensive Rookie of the Year (2015), Defenseman of the Year (2016), Most Sportsmanlike Player (2016) and First All-Star Team Honors (2016, '17).