For a second year running the Macau driver was unstoppable on home soil, executing a perfect lights-to-flag win.
The only time he looked under pressure was right at the start, rival Andy Chang drawing alongside on the run into Lisboa on the first lap.
Leong cleverly held the inside line to ensure he retained the lead, before a devastating first two laps that left him four seconds clear off the field.
At the end of Lap 3 Leong’s life got even easier when Chang was forced to serve a drive-through penalty for a jump start.
That left Leong with a remarkable 25-second advantage, which ballooned out to over half a minute before coming back to 24 seconds as he managed his pace in the closing laps.
Leong is the 10th multiple winner of the Macau Grand Prix and joins the likes of Edoardo Mortara, Felix Rosenqvist and Dan Ticktum as back-to-back winners in the modern era.
He hailed a “perfect” 2021 Macau GP campaign, which stretched back to his four wins at Zhuhai in the recent warm-up event.
“It was perfect from Zhuhai, which is quite amazing,” Leong said.
“I didn’t have any mechanical failures, everything just went fine. It was perfect.
“Without that track time since last year, this really gives me a boost. It shows that I have the ability to go a lot higher, and I’m really eager to show that ability and the talent that I have.
“It’s pumped me up quite a lot.”
Chang had pulled clear of third-placed Li Sicheng before serving his drive-through, but dropped well behind after his unwanted tour of the pitlane.
However he was able to reel in and pass Li by Lap 8, Chang then shading Leong in the fastest lap stakes as he sealed second place.
Post-race he was left to rue a poor first couple of laps – and was left bemused by his penalty.
“It was a tough race,” he said. “At the beginning I drove terribly. My times were 2m31s or something like that, pretty slow.
“At Lisboa [on the first lap] I tried to brake later [than Leong] to overtake as it was my only chance, but it didn’t work.
“Then I received a drive-through penalty. I thought, ‘why have I got a penalty?’.
“After I served it I thought I thought I was fourth or fifth but then I caught Li Sicheng I realised I was in third and if I could overtake him I’d be second.
“I’m happy to finish second.”
Li finished a distant third to mark two Macau GP podiums in as many years, the top three identical to last year’s race.
Jing Ze Feng finished fourth with a charging drive after a first-lap mishap saw him down the end of the run-off area at Lisboa.
He methodically worked his way through the field, grabbing fourth – where he started – on the final lap.
Li Chao finished fifth while Shang Zong Yi dropped from fourth to sixth on the last of the 12 laps.
Lyu Jin Xi, Brian Lee, Wei Chao Yin and Peng Li Shin rounded out the Top 10 for the 2021 running of the prestigious race.
Two drivers weren’t classified, Wong Yiu Ming and Patrick Tsang both crashing out at Lisboa on the opening lap.