Wall scored a season-high 35 points and the Wizards handed the Cavaliers their first home loss of the season, 97-85.
The Wizards, who never trailed, scored the first 10 points of the game and went on a 9-0 run to begin the second half in snapping a four-game losing streak.
The Cavaliers fell to 9-1 at home, where they had won 29 of 30 dating to last season.
The Wizards seemed unlikely candidates to win in Cleveland. Wall has heard criticism for being too passive and came into the game shooting 39 percent. He did something about it Tuesday, going 14 of 24 from the field with 10 assists.
"I read everything, I hear everything that people say, because I like it," Wall said. "You've got to take the criticism if you're going to take the praise."
Cleveland coach David Blatt praised Wall's performance.
"We didn't do a very good job with him regardless of who was guarding him, let's be honest," Blatt said. "The guy had a great game."
Bradley Beal scored 18 and Marcin Gortat added 15 points with 11 rebounds for the Wizards.
"We are an unpredictable team," said Gortat, who spoke of the negative atmosphere around the club following Saturday's loss to Toronto. "Last year, we proved we could beat good teams by 20, but we can lose at Philly. We are a crazy team."
Washington went on a 15-2 run in the second quarter to break open a one-point game and led 54-43 at halftime. The Wizards scored the first nine points of the second half to take a 21-point lead.
The Wizards led 69-47 midway through the third quarter, but Matthew Dellavedova scored 10 points in the period, including three 3-pointers. Cleveland got to 78-67, but Washington answered the run and the lead remained in double figures.
Washington made five of its first six shots, prompting the Cavaliers to call timeout less than 3 minutes into the game. Cleveland tied it 14-all, but the Wizards quickly went ahead again.
The Cavaliers trailed 37-36 midway through the second quarter, but Wall scored 13 points in the period and Washington took control.
"They were quicker," James said. "They were faster to the ball, with the ball. They were a step quicker than us. They beat us pretty good."
Dellavedova finished with 15 points and J.R. Smith added 13.
Cleveland committed 19 turnovers, including a season-high nine by James, that led to 25 points for the Wizards.
ROUGH ROAD
Wall's shooting percentage is a career worst, as is his 16.1 point average.
"Every team is trying to make me make jump shots this year, so I was just being aggressive and getting to the basket. I got into a rhythm early and it helped us get going," he said.