During the 1999-2000 season O'Sullivan won two titles valid for the Ranking: the China Open, which ended Stephen Lee 9-5, and the Scottish Open, which ended Mark Williams 9-1.
Durante la stagione 1999-2000 O'Sullivan vince due tornei validi per il Ranking: il China Open, battendo in finale Stephen Lee 9-5, e lo Scottish Open battendo in finale Mark Williams 9-1.