Australia's Robertson led 5-2 during the first session but the 40-year-old O'Sullivan won seven frames in a row to clinch the title, Xinhua reported.
The Rocket matched the record set by John Higgins last year, and the 28th ranking title of his career, equalling the tallies of Higgins and Steve Davis. Only Stephen Hendry is ahead of that formidable trio on 36.
The 60,000-pound top prize moves O'Sulilivan up one place to fourth in the world rankings.(IANS)