The ex-NY Jets running back signed a 1-year deal with the defending Super Bowl champs, after being cut by Gang Green earlier this week.

You know the backstory ... the Jets suck. Bell was unhappy. The Jets decided to get him outta there before he became a bigger problem.

Bell was reportedly deciding between 3 teams -- the Chiefs, Miami Dolphins and Buffalo Bills ... and ultimately decided the best fit was in K.C.

The best part ... the Chiefs play the Jets in Week 8 -- so, that should be fun!

Bell tweeted about the move Thursday afternoon -- saying, "Kansas City, #ChiefsKingdom thank you for the opportunity. Let’s go!"

Bell should have an immediate impact on the Chiefs running game -- currently ranked 19th in the league with an average of 108 rushing yards per game.

The starting back is rookie sensation Clyde Edwards-Helaire -- who can ball -- but let's face it, he could probably use the help.

Question is ... can Bell reclaim his place as one of the top backs in the NFL? Or are his best days behind him?