Coles enjoyed a one-stroke lead over Molder at the start of the final round but it was the American who stormed out of the gates. Molder grabbed the lead with birdies on the first three holes while Coles tried to keep pace with a birdie at the second.
The Australian never lost his composure and regained a share of the lead when Molder ran into trouble with a bogey at the eighth. Coles then birdied the ninth to take the outright lead at minus-11.
Gavin talks about his win
The 33-year-old bogeyed the 10th but responded with back-to-back birdies from the 11th to open a two-shot lead over Molder. However, his bid for a victory would be challenged at the par-3 14th.
Coles struggled to a double-bogey while Molder rolled home a 40-footer for birdie and a three-shot swing on the hole. The American held a one-stroke lead over Coles heading into the final stretch, but the advantage proved to be short lived.
The former Yellow Jacket dropped a shot on the following hole for his first of four consecutive bogeys to close out the round and open the door for Coles.
Coles bogeyed the 15th but coasted at even-par over the final three holes for a breakthrough win at the event co-sanctioned by the Buy.Com and PGA Australasian Tours.
'This has changed my life in more ways than one,' said Coles. 'I was just thinking about process, process, process. It's a lot easier than it sounds I know, but I just thought about my swing and nothing else coming home.'
Australia's Peter Fowler finished alone in third at 6-under 282 after a round of 73 while fellow countryman Peter O'Malley (73) was three shots further back at 3-under 285. O'Malley, who had a four-shot lead after the second round, was joined by Stephen Leaney in a tie for fourth.
American Jason Gore shot a 3-under 69 to finish at 2-under 286 alongside Trevor Dodds (71) of Namibia and the Australian trio of Terry Price (69), Mark Hensby (73), and Paul Sheehan (69).
Full field scores from the Jacob's Creek Open Championship