Sources say that the free agent center has agreed to a contract with the Flames.
A league source says the contract has a $7 million cap hit.
According to multiple reports, the Flames are trying to make salary-cap space for Kadri by trading Sean Monahan to Montreal.
Kadri had a career-best 87 points in 71 games for the Colorado Avs. He has 512 points in 739 games in the NHL over the course of 13 years.
Kadri meshed well with Colorado's power-play units and raised his profile even more in the playoffs after returning from a thumb injury to score an overtime goal in the Stanley Cup Final. Kadri was hurt in the Western Conference finals when Evander Kane rammed him into the wall. They went on to win that series.
Kadri was one of the top free agents on the market. There were rumors that Kadri could have a deal in place with the New York Islanders and who would have needed to clear cap space to acquire him.
Kadri was brought in by the Flames, who lost their two leading scorer. Johnny Gaudreau left the franchise after nine seasons to sign with the Blue Jackets. Matthew Tkachuk was traded to the Florida panthers in July after he made it clear he wasn't looking to stay in calgary long-term.
The signing of Kadri is a continuation of the aggressive Plan B that the Flames have been pursuing. The cap hit on the contract was $10.5 million, which was supposed to be the replacement for Gaudreau.
He has been with the Flames for nine years and has played in all of them. When he was the team's top center, he suffered a number of injuries that affected his output. He was a healthy scratch for the majority of the season before he had hip surgery. The last season of a seven-year deal that carries a $6.300 million cap hit for the sixth overall pick in the 2013 draft is just around the corner.