The 25-year-old followed his one-shot Africa Open win eight days ago with a six-stroke triumph in the Joburg Open at Royal Johannesburg and Kensington.
Northern Ireland's Darren Clarke, who let slip a chance to apply real pressure midway through the front nine, chipped in for eagle on the last to tie for second place with Schwartzel's compatriot Keith Horne, round in a best-of-the-day 64. Rotherham's Danny Willett continued his good form into the New Year when he tied for fourth with South African James Kamte after a final round of 68.
Harrogate's John Parry was three shots back from Willett after an impressive 69 on the last day while Sheffield's Neil Cheetham was one adrift of Parry.
Schwartzel's notable double, completed with a polished 66, takes him to his best position in the world – possibly as high as 35th depending on what happens on the US Tour. It should also lead to him making a
Masters debut at Augusta in April. The top 50 the week before the first major of the season all qualify.
He has the talent to go much higher, though. He was 23 under here and is 52 under for his last 11 competitive rounds.
The margin of victory equalled the biggest of last season and Schwartzel said: "It's been a fantastic two weeks for me. I played good last week and it definitely carried over.
"I played pretty much flawless golf and I don't know what it comes down to – maybe a good positive frame of mind when you hit a bad shot.
"I'm leading the Order of Merit, but it's still early days and I think this will get me into the Masters. I'm very excited about that."
Within hours of his victory, however, Schwartzel decided he needed a week off and so will not try to become the first player since Seve Ballesteros in 1986 to win three consecutive European Tour events. He will be back for the Qatar Masters starting on Thursday week.
Four behind at the start of a round brought forward because of the threat of further storms, Clarke could easily have closed the gap to one on the long sixth, but missed from six feet.
The Ryder Cup star then three-putted the next and there looked only one winner after that, but the closing eagle earned the 40-year-old Clarke over 107,000.
Schwartzel picked up 185,403, meaning Westwood will begin his defence of the "Race to Dubai" title already more than 400,000 behind.