The 2021 Championship League was a professional ranking snooker tournament that took place from 18 July to 13 August 2021 at the Morningside Arena in Leicester, England.

The event featured 128 players and was played as three rounds of round-robin groups of four, before a best-of-five final.

Kyren Wilson was the defending champion, having defeated Judd Trump 3–1 in the final of the September to October 2020 edition of the tournament.

David Gilbert won the tournament, defeating Mark Allen 3–1 to win his first ranking title.

Group positions were determined by points scored, frame difference and then head-to-head results between players who were tied.

[7] Peter Lines won Group 8 over Mark Williams after winning their match 3–0, despite losing to Jak Jones.

[8] Noppon Saengkham won all three of his matches, including over four-time world champion John Higgins to win Group 9.

This was Saengkham's first professional match since being forced to withdraw from the 2021 World Snooker Championship due to a positive case of COVID-19.

[9] World number 115, Ashley Hugill won Group 24, with wins over John Astley and Stephen Maguire.

[11] Tom Ford won Group A, after he completed a whitewash over world number one Judd Trump.

[11] Ronnie O'Sullivan, who had won Group 32, withdrew from the event, and was replaced by second placed Mark Joyce.

[14] Allen won the first of the stage three groups, completing 3–0 victories over Ford and Wilson, as well as a 3–1 win over Bai Langning.

[15] Despite a loss in the opening match to Cao Yupeng, Gilbert won the second Group after victories over Carter and Ryan Day.

Lu Ning was originally due to take part in this group, but withdrew and was replaced by Ben Fortey.

Zhou Yuelong was originally due to take part in this group, but withdrew and was replaced by Joshua Thomond.

Alfie Burden was originally due to take part in this group, but withdrew and was replaced by Sydney Wilson.

Ng On-yee was originally due to take part in this group, but withdrew and was replaced by Saqib Nasir.

Ronnie O'Sullivan was originally due to take part in this group, but withdrew and was replaced by Mark Joyce.