As a member of the Colorado Avalanche, Girard improved his on-ice success recording career-high numbers in his first three seasons.

He has also competed with Canada men's national junior ice hockey team at the 2015 Hlinka Gretzky Cup where he won a gold medal.

[8] While attending Wilbrod-Dufour Pavilion, he began training with Mathieu Gravel in order to increase his muscular mass and stamina.

[11] After graduating to the Quebec Junior AAA Hockey League (QMAAA), Girard drew interest while playing with the Jonquière Élites.

[15] Girard moved in with power skating coach Julie Robitaille during his rookie season and trained with Mathieu Bellemare, and Bruno-Carl Denis to gain physical strength.

[18] In his first season with the Cataractes, Girard recorded his first career QMJHL goal on November 15, 2014, in overtime to beat the Rouyn-Noranda 5–4.

[34] Girard made his NHL debut during the Predators 2017–18 season home opener on October 10, 2017 against the Philadelphia Flyers.

In his Avalanche debut at Ericsson Globe, Girard played top-pairing minutes and registered an assist, in a 4–3 overtime defeat to the Senators on November 10, 2017.

[44] The Avalanche again qualified for the 2019 Stanley Cup playoffs and Girard was partnered with Erik Johnson in their first round matchup against the Calgary Flames.

[49] Later that month, he played in his 200th career NHL game and became the longest active iron man streak holder on the team.

In his rookie season with the Shawinigan Cataractes, Girard was selected for Team Canada at the World U-17 Hockey Challenge.

Described as a smooth-skating and mobile player, Girard is compared to long-time Chicago Blackhawks defenceman Duncan Keith.

[62] Standing at 5-foot-10 in his draft year, Girard has also drawn comparisons to Brian Campbell due to his stature, "strong edge work and balance.

[65] He was also invited to sit as honorary presidents of the cadet and juvenile division 1 School Hockey Championship with the Quebec Student Sports Network.

In 2019, Girard and his father hosted a pocket game tournament to raise funds towards a cure for cystic fibrosis.

[68] He also donated a portion of his profits from the QMJHL to the Julie Robitaille's School of Power Skating who helped him train.

[69] In 2018, as he was returning from a charity event, Girard fell asleep at the wheel while driving a Chevrolet Camaro and it struck the parapet, causing major damage.