Gilgeous-Alexander, the reigning NBA Most Valuable Player and Finals MVP, scored 31 points with three rebounds and seven assists before sitting out the fourth quarter as the Thunder polished off their sixth straight win.
Two days after they clawed back to beat Sacramento, the Thunder took charge early, building a 59-49 halftime lead and never trailing in the second half.
Isaiah Joe and Ajay Mitchell added 20 points each off the bench for Oklahoma City, who scored 26 points off 23 Wizards turnovers.
The Thunder were again without injured Chet Holmgren and Jalen Williams, and they've been rocked this month by the news that 20-year-old guard Nikola Topic is undergoing treatment for testicular cancer.
But the season debut of Joe, who missed the first five games with a bruised knee, was a welcome jolt of on-court energy.
"He hit the ground running," coach Mark Daigneault said.
"Man, my teammates, I've got to give them all the credit - they find me when I'm open," Joe said in an on-court interview. "The rest, I just had to do my job and make shots."
Turnovers also bedeviled the Golden State Warriors as they dropped a 120-110 decision to the Bucks in Milwaukee, despite the absence of Bucks star Giannis Antetokounmpo.
Warriors star Stephen Curry scored 27 points on eight-of-19 shooting and Jonathan Kuminga added 24 points, but 22 turnovers were too much for Golden State to overcome.
Two-time MVP Antetokounmpo, averaging 36.3 points over the first four games of the season, was a late scratch with a sore left knee.
But Ryan Rollins stepped up with a career-high 32 points to lead the Bucks against his former team.
In a game that featured 16 lead changes, it was the Bucks who put together the more convincing runs. Up 87-84 entering the fourth, Milwaukee never trailed in the final period.
Rollins closed out the win with a step-back three-pointer with 24.8 seconds left to post the first 30-point game of his career.
"Feels great," he said in an on-court interview. "Doesn't get better - we got a W.
"(I was) just out there playing aggressive, looking for my shot, getting downhill, creating stuff for others and myself," he added.
Aggressive mindset
He said the Bucks knew that without Antetokounmpo they had to be aggressive.
"Don't pass up any open shots," he said. "Everybody had that mindset and on defense we just had to pick up full court, play aggressive - that's what we did, we came out and with the W."
The San Antonio Spurs also remained unbeaten, improving to 5-0 for the first time in franchise history with a 107-101 home victory over the Miami Heat.
French star Victor Wembanyama scored 27 points and grabbed his season-high 18 rebounds for the Spurs, adding six assists, a steal and five blocked shots for good measure.
Stephon Castle added 21 points for San Antonio, who beat a Heat team led by Bam Adebayo's 31 points.
The Heat twice took a one-point lead on Adebayo baskets early in the fourth quarter, but Devin Vassell's three-pointer - off a feed from Wembanyama - put San Antonio ahead 93-91 with 5:26 remaining and the Spurs pulled away from there.