Neil Robertson stormed off the blocks in the opening afternoon sessionto lead 3-1, pocketing breaks of 76, 108, and 81, while O'Sullivan got off to a stuttering start, despite managing a 92 break in frame two.
O'Sullivan came back with a break of 67, but lost the final three frames of the session against a tactically strong Robertson to trail 2-6.
O'Sullivan with a spectacular comeback
When Robertson started the evening with a 97 in the second session, the 49-year-old realised the seriousness of the situation and struck back in classic O'Sullivan style.
With breaks of 137, 97, 89, 57, and 80, he won five frames in a row and levelled the 2-7 deficit in no time at all. The Australian only managed two points between frames 10 and 13.
He responded with a nervy 75, but O'Sullivan was unstoppable.
In a 38-minute thriller, "The Rocket" snatched the important 16th frame to equalise again, after which he took the lead for the first time thanks to a frame-deciding 64 break.
Robertson shows nerves of steel
But the final was not over yet - quite the opposite. After O'Sullivan failed to follow up a split, Robertson managed a 101 century break shortly afterwards to force a decider.
O'Sullivan had the better start in the deciding frame, initially taking a 35:0 lead thanks to strong safeties, before opting for a controlled exit after another unsuccessful split.
Robertson got his chance a little later after a safety battle and capitalised on it spectacularly. The Australian turned the deficit around thanks to a 91 break, making him the second winner of the prestigious tournament in Saudi Arabia after Judd Trump last year.
He holed the key ball on the last red, when he actually missed the position. Robertson corrected his mistake with a long red on the green corner pocket to take the title.
Robertson moves up to third place in the first world ranking tournament of the new season and takes home a cheque for £500,000.