Duchene made his Blue Jackets debut against his old team, playing 19:11 in Columbus' 3-0 win over Ottawa on Friday night.
Minor league defenseman Julius Bergman is also heading to the Blue Jackets, while the Senators will receive conditional first-round draft picks in 2019 and 2020, and prospects Vitalii Abramov and Jonathan Davidsson in return. The 2019 pick is top-three protected, and the 2020 pick is dependent on Duchene re-signing in Columbus.
Duchene, 28, is on the move again, joining his third team in two seasons after being part of an early-season trade in 2017-18 that sent him to the Senators from the Colorado Avalanche.
He has posted 27 goals and 31 assists in 51 games this season. Duchene missed two weeks in December with a lower-body injury.
In a pair of tweets, Duchene thanked the Senators organization and the team's fans, then expressed excitement about joining the Blue Jackets for a potential playoff run.
@BlueJacketsNHL can't wait to get started! Excited to join such a great team... let's get in a spot and go for a run!— Matt Duchene (@Matt9Duchene) February 22, 2019
Duchene was one of seven Senators players who were recorded in October criticizing the team's poor play and assistant coach Marty Raymond. In the video, which was posted online, Duchene admitted to not paying attention during meetings Raymond led.
The players later apologized for their criticisms.
The Blue Jackets have yet to win a playoff series in their 17-year history, and this could be their chance to break through if they choose to keep left winger Artemi Panarin, who has said he will enter free agency after the season, and goalie Sergei Bobrovsky. Columbus entered Friday a point behind the Carolina Hurricanes for the second wild-card spot in the Eastern Conference.
Columbus badly needed another playmaking center behind top-liner Pierre-Luc Dubois.
Boone Jenner was pressed into action as the second-line center this season but has battled injuries. Coach John Tortorella has expressed frustration with the lack of production from centers Alexander Wennberg and Brandon Dubinsky.
Wennberg finished the 2016-17 season with 59 points, but his performance has dropped off. He and Dubinsky have combined for seven goals and 34 points this season.
A two-time All-Star, Duchene has 228 goals and 307 assists in 704 career NHL games with Ottawa and Colorado. This season, he has won 55 percent of his faceoffs and is averaging 19:15 of ice time.
The Senators are at the bottom of the NHL standings, and a full-bore rebuild is expected.
"When we acquired Matt in November of 2017, we had hoped his addition would drive us to another deep playoff run," Ottawa general manager Pierre Dorion said. "Obviously that did not materialize. More than a year ago, we shifted our focus to a proper rebuild of the entire organization. Our desire was to have Matt be part of this, and as such, we approached him with a fair and comprehensive contract offer to remain a Senator for the long term.
"As soon as it was determined that he did not want to be part of our rebuild, we shifted our focus to see what assets we could acquire in exchange for Matt that would help grow our pipeline of potential."
Abramov, 20, a winger, had 12 goals and 10 assists in 54 games for the AHL's Cleveland Monsters this season. Davidsson, 21, has 10 goals and 10 assists in 35 games during the forward's fourth season with Djurgarden of the Swedish Hockey League.
The Associated Press contributed to this report.