Chabot, a defenseman taken by the Ottawa Senators in the first round (No. 18) of the 2015 NHL Draft, had a solid rookie season in 2017-18, finishing with 25 points (nine goals, 16 assists) in 63 games.
Chabot had his breakout season in 2018-19, finishing with 55 points (14 goals, 41 assists) in 70 games, ranking him 10th among NHL defensemen. He also played in his first NHL All-Star Game. In September 2019, he signed an eight-year, $64 million contract with the Senators. Established as one of the Senators' leaders, Chabot had 39 points (six goals, 33 assists) in 71 games in 2019-20. On Dec. 16, 2019, Chabot played 37:50 in ice time in a 4-3 overtime loss to the Tampa Bay Lightning, leading any other skater on the team by more than 11 minutes. It was the second-highest mark in ice time to Dennis Wideman, who played 38:05 in a shootout loss to the Vancouver Canucks for the Calgary Flames in 2014.