Hawkins stole the first two frames of the final session to close the gap to three frames at 15 - 12.
But defending champion O'Sullivan secured his fifth world title as he took the next three deciding frames.
With several stunning breaks the 37-year-old defeated Hawkins 18 - 12.
His latest stunning victory comes after O'Sullivan took a year away from the sport to try and deal with personal issues.
He was installed as overwhelming favourite against the 34-year-old Hawkins, who, before this year, had never got past the last 16 in seven attempts.
Now a five-time world champion, Ronnie 'The Rocket' O'Sullivan is to appear at the Waterfront Hall in Belfast on June 4 as part of the Snooker Legends 2013 tour.
He'll be joined by fellow former world champions and legends of the game including Stephen Hendry, Ken Doherty and Jimmy White.
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