Paul Pierce and Kevin Garnett also had double-doubles for Boston, which remains tied with Miami for the Eastern Conference's second spot. The Heat, who host the Celtics on Sunday, beat Charlotte 112-103.
Pierce had 22 points and 12 rebounds, and Garnett added 15 points and 11 boards. Ray Allen had 13 points, but was just 1 for 6 from 3-point range.
Andray Blatche led the Wizards with 20 points and 10 rebounds, John Wall scored 20 and Jordan Crawford had 19.
The Celtics never trailed and had a fairly easy time as both teams hardly dug-in defensively for most of the first three quarters.
Boston, which shot 59 percent and led by three at the half, scored the first seven points of the third quarter to open its first double-digit lead of the game, 66-56, on Garnett's three-point play.
Garnett, trailing on a fastbreak, was grabbed as he went up for a shot. The ball fell through as he was falling to the floor, and Garnett then pounded his chest while lying on the floor, bringing loud cheers from a relatively listless crowd. The Celtics pushed it to 79-67 on Rondo's spinning drive in the lane, but Washington scored the next seven points.
The Celtics led 83-75 after three quarters.
Washington did close it to 87-83 on Crawford's breakaway dunk with a little over seven minutes to play, but Rondo, Allen and Pierce followed with baskets to push Boston up by 10 with 3 1/2 minutes left.
Boston then tightened up defensively and the Wizards never threatened the rest of the way.
Boston started the game quickly, opening a 12-point lead midway into the opening quarter before the Wizards closed it to 28-23 after one.
The Celtics had opened a nine-point edge on Pierce's free throw early in the second, but the Wizards whittled it to 59-56 at halftime.
Boston F-C Jermaine O'Neal was given the night off to rest with the team playing four games in five days. He played the last five after missing 36 due to a sore left knee. … Boston G Delonte West was whistled for a pair of technicals by referee Josh Tiven and ejected in the second quarter. … Blatche averaged 27.5 points and 14 rebounds in his previous four games. … The Wizards fell to 0-9 on the road against Atlantic Division teams, but they are 7-1 at home.