Mike Florio of Pro Football Talk first reported the signing. Terms of the deal have yet to be announced.
The Chiefs' failure to re-sign Poe isn't for lack of trying. Terez A. Paylor of the Kansas City Star first reported in February 2016 the two parties were at the negotiating table.
Chiefs general manager John Dorsey praised Poe but acknowledged a new contract was far from a done deal: "We've talked, we've talked more than once. I have great affection for Dontari Poe. I think he represents everything we want to do, culturally. I think he's a good football player. We will continue this process. Right now, I'm concentrating on other things. But eventually, we'll get to that."
When the Chiefs declined to use the franchise tag on Poe, his exit looked increasingly likely. Kansas City also spent some of its available salary cap to tie down safety Eric Berry. USA Today's Tom Pelissero reported he signed a six-year, $78 million deal with the team.
CBS Sports' Jason La Canfora noted how many suitors were lining up to jostle for Poe's services:
Kansas City selected Poe 11th overall in the 2012 draft, and he has since become one of the NFL's better defensive tackles. He has 200 combined tackles and 13.0 sacks in 78 career regular-season games.
The Chiefs have also used Poe in goal-line situations. He has two rushing touchdowns the last two years, and he threw a two-yard touchdown pass to Demetrius Harris in Kansas City's Week 16 win over the Denver Broncos.
NFL Network shared a replay of the score:
SB Nation's Stephen White explained last January how Poe's versatility made him a vital cog in the team's defense:
Poe, however, was worth his first-round slot because he is the rare enormous human being who can also run like a deer, really fat deer, but a deer all the same. He doesn't have to come out on passing downs because even though his listed weight is 346 pounds -- which probably means he is a lot closer to 360 by this point of the season -- he is still explosive enough and quick enough to be able to get pressure with power, as well as with finesse.
Against the Texans last Saturday, Poe was in for eight out of 10 third downs before the Chiefs put in their backups on defense. That underscores how they view him as much more than just a run stuffer.
Despite his value to the team, the Chiefs had a tough decision on whether they were going to commit to Poe for the long term, especially since Dorsey had already earmarked a new contract for Berry. According to Spotrac, the Chiefs only have a little over $7.2 million in available salary cap.
Once a bidding war for Poe began, Kansas City was priced out of the market.
Atlanta's run defense wasn't a huge handicap for the Falcons as they captured the NFC crown. The Falcons allowed 104.5 yards a game on the ground, 17th in the NFL, but ranked 25th in adjusted line yards, per Football Outsiders.
It's easy to point fingers following the Falcons' collapse in the Super Bowl, but the team didn't need a radical overhaul this offseason to get into position to reach the championship game again.
At the same time, signing Poe is a message from general manager Thomas Dimitroff that Atlanta will do everything it can to capitalize on its title window.