NBA Most Valuable Player Shai Gilgeous-Alexander scored 28 points to lead the reigning NBA champion Thunder, who improved to 24-1 to equal the best 25-game start to a season in league history.
They dominated from start to finish to book their place in the final four of the in-season tournament in Las Vegas, where they will take on the Spurs on Saturday.
In Los Angeles, Stephon Castle scored 30 points and grabbed 10 rebounds and De'Aaron Fox added 20 to lead San Antonio, who beat the Lakers despite the continued absence of French superstar Victor Wembanyama.
Wembanyama missed his 12th game with a calf injury, but San Antonio have won nine of their last 12, and coach Mitch Johnson said before the contest that Wembanyama was "very, very close" to a return.
Seven Spurs players - including three reserves - scored in double figures as San Antonio withstood a 35-point performance from Lakers star Luka Doncic.
"We all just want to win," Fox said. "We don't care who does it. We just want to get it done at the end of the day.
"So we have a very versatile team, very deep team. So it's a lot of guys that can get it done every night."
Marcus Smart returned from injury to score 26 off the bench for the Lakers and LeBron James added 19, but Los Angeles struggled to find a way to slow down the speedy Spurs, who held the advantage in fastbreak points and second-chance points and scored 16 points off 11 Lakers turnovers.
The Spurs shrugged off a slow start and followed a late first-quarter surge with an 8-0 run to start the second.
Trailing by as many as 24 early in the fourth quarter, the Lakers cut the deficit to eight, but the Spurs had an answer to every push Los Angeles made.
"We had some good moments, but the majority of the game we were playing uphill too much," James said.
'Play through our comfort zone'
On Wednesday's evidence, few would bet against Oklahoma City completing an NBA Finals-NBA Cup double after a superb performance before their home crowd at the Paycom Centre.
"We hold ourselves to a high standard and most importantly it's about us getting better," Gilgeous-Alexander said after an offensive display that included 22 Thunder three-pointers.
"We just moved the ball really well. Played together, very decisive on offence and tried to play through our comfort zone and when we do that, we're a pretty good offence," added Gilgeous-Alexander, who has now scored 20 points or more in 96 consecutive games.
Oklahoma City are aiming to go one better in the NBA Cup than they did last season, when they reached the final only to be upset by the Milwaukee Bucks.
"We should be in a good position - we've got a lot better since last year," Gilgeous-Alexander said.
The Thunder blowout was all but assured after a devastating 38-point first quarter, which they followed with 36 points in the second to reach half-time with a commanding 74-48 lead.
Chet Holmgren was a perfect 4-of-4 from three-point range on the way to 24 points with eight rebounds and three blocks.
Holmgren was also at the centre of a third-quarter flashpoint, with frustrated Suns point guard Grayson Allen getting ejected for a rough body check on the towering Thunder centre.
Oklahoma City's start to the season equals the 24-1 record compiled by the Golden State Warriors at the start of the 2015-2016 campaign, when the club went on to finish with a history-making 73-9 regular-season record.
