Meloche was drafted by the Baie-Comeau Drakkar in the 1st round of the 2013 QMJHL Entry Draft. During his first season with Baie-Comeau, Meloche scored 25 points in 54 games to set a franchise record for most points by a rookie defenceman, and his outstanding play was recognized when he was named to the 2013–14 QMJHL All-Rookie Team. The following season he was chosen to play with the Canada men's national under-18 ice hockey team at the 2014 Ivan Hlinka Memorial Tournament where he helped Canada win the gold medal. Meloche was also named to the play with the QMJHL All-Stars at the 2014 Subway Super Series, and was selected to participate in the 2015 CHL/NHL Top Prospects Game. Originally rated as a top prospect who was projected to be a possible first round selection in the 2015 NHL Entry Draft. Meloche was subsequently selected 40th overall by the Colorado Avalanche. After attending the Avalanche's 2015 training camp, Meloche began the 2015–16 season in his third year with a rebuilding Drakkar. Despite languishing in the standings, Meloche was leading the defense in scoring with 16 points in 25 games before he was traded by Baie-Comeau to title contenders, Gatineau Olympiques, in exchange for a prospect and two draft picks on December 16, 2015. In being depended upon in a more defensive orientated role with the Olympiques, Meloche contributed with 5 goals and 17 points to end the regular season. He added three points in 9 post-season games before the Olympiques were eliminated in the second-round. In his final junior season in 2016–17, Meloche was unable to prevent Gatineau from a slow start in the standings. Despite leading the blueline in scoring with 21 points in 26 games, Meloche was again traded to a title contender, in a seven player deal with the Charlottetown Islanders on December 21, 2016. On March 6, 2017, it was announced that Meloche signed his first NHL contract, agreeing to a three-year entry-level deal with the Colorado Avalanche. Having completed his junior career, Meloche attended the 2017 Colorado Avalanche training camp and played in the opening pre-season game before he was reassigned to AHL affiliate, the San Antonio Rampage, on September 20, 2017. Prior to the 2019–20 season, unable to make his breakthrough to the NHL with the Avalanche, Meloche was traded to the San Jose Sharks in exchange for Antoine Bibeau on September 27, 2019.
