Jeremy Lamb added a career-high 22 points (on 8 of 10 shooting) and five assists for Oklahoma City, which has the NBA's best record at 25-5. The Thunder have won 12 of their last 13 and 20 of their last 22 games.
Reggie Jackson, starting in Westbrook's place, had 16 points and eight assists as the Thunder never trailed and led by as many as 32 points against a team they beat in six games in the first round of last season's playoffs.
Durant said the experience of playing without Westbrook for the final four games of that series and the rest of the playoffs prepared the Thunder for what they must face now.
"It's still tough not having him here, but we know what we have to do now," Durant said. "We learned from our mistakes last time. Hopefully we just keep getting better and when he comes back it's kind of a seamless transition for us."
Oklahoma City shot 57 percent from the field (47 of 82) in dealing the Rockets their worst loss of the season.
"That team is a very, very high-powered offense," Durant said. "They're so quick up the floor. We just wanted to let them see bodies and just play hard. We've got to do a better job (defensively) but tonight was a step in the right direction."
Aaron Brooks had 17 points and Chandler Parsons scored 15 for Houston, which was playing its fourth game in five days. The Rockets, who had a three-game winning streak snapped, missed their first 12 shots and shot 36.5 percent from the field (31 of 85).
Houston coach Kevin McHale wouldn't use fatigue as an excuse for the Rockets' performance.
"You're playing basketball," McHale said, shaking his head. "You're not logging tall timbers, believe me. Four games in five nights ... next question.
"We couldn't stop them. We couldn't run. We had nothing."
Oklahoma City is 3-2 this season without Westbrook. The All-Star point guard underwent arthroscopic knee surgery on Friday, his third surgery since last April, when he tore his meniscus after Houston guard Patrick Beverley banged knees with him as Westbrook tried to call a timeout in Game 2 of last season's playoff series.
The Thunder have said Westbrook's latest surgery will sideline him until after the All-Star break. Oklahoma City won 89-85 at Charlotte on Friday night in their first game since that surgery, as Durant had 34 points and 12 rebounds.
"The team's going to pick it up," Jackson said. "We're going to do things collectively. We're going to find a way to play, but we all know our limitations. We all know what we're good at. We don't know, necessarily, where we'll get it from each and every night, but we're just trying to go ahead and find our shots and continue to take them."
Oklahoma City jumped to a 13-0 lead as the Rockets failed to score until Howard hit a 3-foot jump hook with 5:27 left in the first quarter.
The Thunder extended their lead to 22-5 on a driving layup by Thabo Sefolosha and were up 26-14 at the end of the quarter. The Thunder's lead stayed in double digits most of the second quarter and Oklahoma City led 56-44 at halftime.
Parsons opened the second half with a corner 3-pointer to pull the Rockets within nine points, but Durant hit two 3-pointers and Jackson had another during a 15-0 run to give Oklahoma City its biggest lead to that point at 71-47.
Houston came no closer than 17 points the rest of the way.
"We just had a tough time making shots tonight," Howard said. "That happens. We've got to come out better. We've got to find a way to get ourselves going. That's it."
Houston also struggled at the free throw line, hitting just 17 of 31 attempts (54.8 percent).
Sefolosha scored 13 points, one off his season high, for Oklahoma City. Omri Casspi added 15 points for the Rockets.
Harden, a former fan favorite with the Thunder before being traded to Houston before last season, received a strong mix of boos and cheers during pregame introductions. Right before the tipoff, Harden walked over to the Thunder bench to greet some of his former teammates and coaches ... Houston's 14-point first quarter was a season low and the Rockets' second-lowest quarter of the season . Brooks hit a halfcourt shot at the end of the third quarter, which pulled the Rockets within 90-70.