In 2021 Carlsen was to defend his title for the fourth time, this time against Ian Nepomniachtchi, after winning the previous world championship match against Fabiano Caruana on rapid tiebreaks (see Game Collection: Carlsen in World Championships: the 2018 match).

Nepomniachtchi qualified by winning the long, interrupted mid-tournament due to the COVID-19 pandemic, World Championship Candidates (2020/21).

And to the Candidates he qualified by finishing second in the 2019 FIDE Grand Prix behind Alexander Grischuk (winner in Moscow (FIDE Grand Prix Moscow (2019)), eliminated in the first round in Hamburg by Jan-Krzysztof Duda (Grand Prix Hamburg (2019)), winner in Jerusalem (Grand Prix Jerusalem (2019))).

To the Grand Prix Nepomniachtchi qualified by rating.

Game 6, won by Carlsen, broke the record for the longest world championship game ever, at 136 moves. Previous record holder was Korchnoi vs Karpov, 1978 (124 moves); previous longest decisive world championship game was Kasparov vs Karpov, 1990 (102 moves).

Carlsen won the match with three games to spare, 7.5-3.5 (+4 -0 =7)