The 35-year-old, who won last week's Ballantine's Championship in South Korea in a play-off, had a much smoother ride at the Tianjin Binhai Lake Golf Club as he surged ahead of the chasing pack with six birdies over his first 14 holes.
A pair of bogeys on the closing holes made little difference as Rumford carded a four-under-par 68 for a 16-under 272 total, four clear of Finland's Mikko Ilonen.
The Perth golfer's fifth European Tour title took him to the top of the money list, a huge leap from his 138th position a fortnight back.
"As with last week I'm kind of speechless at the moment," he said at the co-sanctioned event.
"It's quite surreal - it's the first time I've actually played the week after a win so I'm more than pleased. It's hard to get my head around it at the moment."
Ilonen, who won the last of his two European Tour titles in 2007, has to wait longer to end his drought after mixing four birdies with three bogeys for a final round one-under 71.
Ilonen, who finished ninth in Qatar and second in Morocco this season, cut Rumford's lead to one after birdies on the 10th and 11th, but two bogeys on 13th and 14th dropped him back as the Australian went on a birdie spree.
"Mikko certainly put the pressure on me through the turn there, and obviously he was driving well... but it's amazing this game, how quickly it can turn," Rumford added.
"Last week on 17 it turned for the worst and here, in the space of just three or four holes, all I had to do was finish it off."
France's Victor Dubuisson finished third on 11-under while first-round leader Robert-Jan Derksen was fourth, a shot further back.
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