Jamison scored a season-high 30 points, Andray Blatche added 16 points and eight rebounds and the Wizards snapped a five-game road losing streak with an 89-87 victory.
The Wizards had lost 11 of their previous 13, but found a way to hold off Houston, even after Jamison left the game briefly in the fourth quarter with a left knee injury.
"We just fought through it," said Jamison, who also grabbed 12 rebounds. "Nobody was hanging their heads down or second-guessing whether we had a chance to win. We played confident tonight."
Nick Young added 14 points as the Wizards ended a seven-game losing streak to the Rockets and won in Houston for the first time since 2001.
Butler, Washington's leading scorer, sat out for the second straight game with a sprained left ankle. But the Rockets sputtered on offense most of the night and Washington took a 10-point lead into the final quarter.
Blatche said the Wizards drew confidence from a 93-89 loss in Cleveland last Thursday. They beat Oklahoma City on Saturday night before winning on Monday for their first two-game victory streak of the season.
"It's about effort," Blatche said. "We've turned it around since the Cleveland game. We all came out together with a lot of effort, played hard and we realized what kind of team we can be. We're just building from that game."
Ron Artest scored 20 points, but also had six turnovers for the Rockets, who had a seven-game home winning streak snapped by the worst team in the Eastern Conference.
The Rockets have been affected by injuries all season, but they couldn't use that as an excuse. Tracy McGrady was back after sitting out Saturday's win over Utah with a sore left knee.
"The energy wasn't there," said McGrady. "We weren't making shots. We just weren't a smart basketball team."
Houston rallied to take a slim lead in the fourth quarter before collapsing again at the end.
DeShawn Stevenson made a tough fadeaway jumper from the corner with 1:12 left, then sank a free throw with 39 seconds remaining to stretch Washington's lead to 89-85.
McGrady made a jumper with 32 seconds left and Artest stole the ball from Jamison with 10 seconds left, giving the Rockets a chance to tie. Out of a timeout, Yao Ming missed a shot from the baseline and the ball bounced out of bounds as time expired.
"We just thought that we could turn it on in the fourth quarter and win this ballgame against a team that doesn't really show that they are as good team," McGrady said. "It really backfired on us."
McGrady scored 15 points on 6-of-17 shooting and Yao was held to 12 points on 4-for-14 shooting.
The Rockets were sluggish from the start, missing nine of their first 15 shots and committing three turnovers in the first nine minutes. The Wizards could've built an earlier lead if they hadn't missed 12 of their first 17 shots.
Houston had seven turnovers - four by Artest - in the first seven minutes of the second quarter and the Wizards built a 38-27 lead.
The Rockets trailed 45-36 at the break after scoring a season-low 14 points in the quarter. They shot 33 percent from the field and were outscored 28-8 in the paint in the half.
Carl Landry drove for a dunk and Luis Scola took a charge early in the fourth to finally kick-start the Rockets. Artest made a jumper and a 3-pointer to cut Houston's deficit to 74-71. Brent Barry's 3-pointer a few minutes later gave Houston a 75-74 lead.
Jamison knocked knees with a Rockets player and left the game near the 8-minute mark. The Rockets still couldn't shake the Wizards, who cut the lead to 83-82 on Blatche's basket inside with 5:18 remaining.
Jamison returned with 4:56 left and tipped in a miss. He was then fouled by Scola, bent over in pain and went to the bench to have a trainer wrap tape around the knee.
"Luckily, it wasn't anything more severe," Jamison said. "I was still able to go out and contribute a little bit."
- The Wizards earned their first victory at the Toyota Center.
- Washington went 1-for-11 from 3-point range.
- The Rockets' 36 first-half points were a season low.