The Bobcats let a six-point lead get away in the final 1:14, but Walker salvaged the victory with the last of his 22 points.
Charlotte, which led by 16 going into the fourth quarter, won its third in a row to climb a gave above the breakeven mark. The Timberwolves lost at home for the first time in four appearances this season.
Dante Cunningham made a dunk for Minnesota with 74 seconds to play, bringing the Timberwolves within four points.
Alexey Shved added a layup with 47 seconds remaining to get Minnesota within two and Luke Ridnour tacked on a technical free throw for the Timberwolves with 38 seconds to go after the Bobcats had called a time out when they had none remaining.
Derrick Williams could have put Minnesota in front with 12 seconds left, but he hit only 1-of-2 free throws that forged an 87-87 tie.
Charlotte missed two field goal attempts down the stretch, failed on two free throw tries and turned the ball over once, but the Bobcats finally came through when Walker made his game-winning shot.