Head to Head
| Championship League Snooker | 2021/02/11 15:45 | Ronnie O'Sullivan v Mark Williams | 1-3 |
| World Championship 2020 | 2020/08/11 18:00 | Mark Williams v Ronnie O'Sullivan | 10-13 |
| Gibraltar Open 2019 | 2017/11/16 11:30 | Ronnie O'Sullivan v Mark Williams | 5-1 |
| UK Championship | 2016/12/02 19:00 | Mark Williams v Ronnie O'Sullivan | 2-6 |
| Championship League Snooker | 2016/01/04 12:00 | Ronnie O'Sullivan v Mark Williams | 3-2 |
Home History
| Welsh Open 2021 | 2021/02/19 19:00 | Mark Williams v Tom Ford | 5-4 |
| Welsh Open 2021 | 2021/02/18 19:00 | Hossein Vafaei v Mark Williams | 2-4 |
| Welsh Open 2021 | 2021/02/18 10:00 | Mark Williams v Joe Perry | 4-2 |
| Welsh Open 2021 | 2021/02/17 14:40 | Mark Williams v Liam Highfield | 4-1 |
| Welsh Open 2021 | 2021/02/16 13:00 | Mark Williams v Michael White | 4-1 |
| Championship League Snooker | 2021/02/13 19:30 | Ali Carter v Mark Williams | 3-2 |
| Championship League Snooker | 2021/02/13 18:00 | Mark Williams v David Gilbert | 3-1 |
| Championship League Snooker | 2021/02/13 14:45 | Mark Williams v Anthony McGill | 2-3 |
Away History
| Welsh Open 2021 | 2021/02/18 20:55 | Zhou Yuelong v Ronnie O'Sullivan | 1-4 |
| Welsh Open 2021 | 2021/02/18 14:50 | Martin Gould v Ronnie O'Sullivan | 0-4 |
| Welsh Open 2021 | 2021/02/17 13:00 | Jimmy White v Ronnie O'Sullivan | 0-4 |
| Welsh Open 2021 | 2021/02/16 14:50 | Ronnie O'Sullivan v Robbie Williams | 4-0 |
| Championship League Snooker | 2021/02/11 19:25 | Ronnie O'Sullivan v Kyren Wilson | 2-3 |
| Championship League Snooker | 2021/02/11 18:00 | Ronnie O'Sullivan v Barry Hawkins | 1-3 |
| Championship League Snooker | 2021/02/11 15:45 | Ronnie O'Sullivan v Mark Williams | 1-3 |
| Championship League Snooker | 2021/02/10 20:40 | Ronnie O'Sullivan v Mark Selby | 3-1 |