The 2021 FIVB Volleyball Men's U21 World Championship was the 21st edition of the FIVB Volleyball Men's U21 World Championship, contested by the men's national teams under the age of 21 of the members of the FIVB, the sport's global governing body.

[2] But, South Korea and China later withdrew and were replaced by Thailand and Poland respectively.

[3] Teams were seeded in the first two positions of each pool following the serpentine system according to their FIVB U21 World Ranking as of 1 March 2021.

[4] FIVB reserved the right to seed the hosts as head of pools A and B regardless of the U21 World Ranking.

All teams not seeded were drawn to take other available positions in the remaining lines, following the U21 World Ranking.