The defenseman left in the second period of a 4-1 loss to the Columbus Blue Jackets on Wednesday shortly after he was hit by Columbus forward Sean Kuraly.
Ottawa (21-34-5) is seventh in the Atlantic Division. Its last regular-season game is April 29 against the Philadelphia Flyers.
"A fracture in the hand is typically around that timetable (4-6 weeks) and there would be no point (in Chabot returning)," Senators coach D.J. Smith said Thursday. "You wouldn't play him if he was healthy for two games at the end or whatever the case may be."
Chabot, who had an assist Wednesday, scored 34 points (six goals, 28 assists) in 55 games this season and leads the NHL in ice time per game (26:23).
"When 'Chabby' went out, it was a huge hit to us," Smith said. "I could just feel it on the bench emotionally. He does so many things. The word got out in the room after [the second period] that Chabby wouldn't be returning and what the injury was."
Chabot missed four games from Feb. 15-20 with an upper-body injury after taking a hit from Washington Capitals forward Tom Wilson on Feb. 13. He returned and scored two goals in a 4-3 win against the Minnesota Wild on Feb. 22.
"He changes the complexion of our team, obviously," Senators captain Brady Tkachuk said after the win against the Wild. "We know how much he plays and how much he's out there, but yeah, he's a difference-maker. … He took over tonight's game and won it for us."
Smith said defenseman Jake Sanderson, the No. 5 pick in the 2020 NHL Draft who is playing for the University of North Dakota, is injured and may not be ready to report to Ottawa when North Dakota's season ends. Sanderson has scored 26 points (eight goals, 18 assists) in 23 NCAA games this season.
"I really look forward to getting him here and him joining this group," Smith said. "The sooner that he can get out there and get those minutes, the better it is for him, the better it is for us. We think he's a huge part of the future."
Forward Tim Stutzle did not practice Thursday and is day to day with a lower-body injury.
Ottawa hosts Philadelphia on Friday (7 p.m. ET; RDS, TSN5, NBCSP+, ESPN+, NHL LIVE).
