The five-times world champion compiled breaks of 116, 79, 101, 112 and 56 to secure a meeting with Li Hang in the last 16 of the event.
"I played pretty well, I was playing hard match snooker and didn't take many chances," O'Sullivan said afterwards. "When you play more matches that comes automatically, whereas tonight I had to be conscious of not taking on shots to let him in.
"I have to concentrate hard on every shot and think about the consequences. Maybe by the time of the UK Championship or the Masters I'll have played more matches. I was on a roll tonight and wanted to make a century every time I came to the table."
'The Rocket' now has 756 career centuries, 19 behind Stephen Hendry's record of 775.
Earlier in the day, Northern Irishman Joe Swail recorded his best result in year courtesy of a 6-5 win over world number two Neil Robertson.
Swail is a former World Championship semi-finalist, but lost his place on the sport's main tour in 2012. He has won 10 matches in four ranking tournaments this season.
He was 5-3 down, but won the final three frames to progress.
"I'm absolutely delighted," said Swail. "Neil had a few chances to get over the line, but it's not easy out there under pressure. I managed to take mine in the end. I haven't been involved much at the big events in recent years so to come here and beat one of the top players is very good.
"After I fell off the tour, I decided to give snooker one more go, but with no expectations because my level of play had dropped. That took pressure off me.
"I don't care whether I play the world number one or the world number 551 because two years ago I was in a very low place. I'm just glad to be here and competing with the best."