Garnett finished with five points, eight rebounds and two blocks for the Timberwolves, who notched their second victory in three games.
Kevin Martin led the Timberwolves with 28 points on 10-of-15 shooting, Andrew Wiggins added 19 points and Nikola Pekovic contributed 15 points and 13 rebounds.
Washington grabbed an early 15-point lead, but soon collapsed into a fifth straight defeat.
Otto Porter led the Wizards with 13 points, Nene chipped in with 12, and Garrett Temple netted 11.
The night belonged to Garnett, back in a Timberwolves uniform for the first time since 2007 after a trade-deadline move from the Brooklyn Nets.
Since departing Minnesota, Garnett has won an NBA title in 2008 with the Boston Celtics.
But the 38-year-old Garnett rejoined a T-Wolves team that hasn’t made the playoffs since his departure.
The team are languishing in last place in the Western Conference, but hope Garnett’s leadership can help the talented youngsters they have gathered learn to contend.
Garnett was honored with a video tribute during player introductions, receiving a standing ovation.
From there things went downhill quickly. Martin lost the ball on the Timberwolves’ first possession, and the hosts went more than half of the opening period before Pekovic hit their first shot from the floor, a layup at 5:27 that made it a 13-3 game.
Marcin Gortat’s three-point play gave Washington a 15-point lead before the Timberwolves battled back to cut the gap to 20-11 after the first quarter.
An 8-0 scoring run in the second quarter pulled Minnesota within one and they were tied 42-42 at halftime.
Wiggins’ dunk to open the third quarter gave Minnesota their first lead of the game. He scored seven points in less than a minute later in the frame as Minnesota slowly took control.
The Timberwolves finished with their largest margin of victory this season, surpassing a 16-point victory over the New York Knicks in November. – Agence France-Presse