The 2021 season was the Kansas City Chiefs' 52nd season in the National Football League (NFL), their 62nd overall and their ninth under head coach Andy Reid, looking to become the fourth team in NFL history to make three straight Super Bowls.

The Chiefs would host their fourth straight conference championship but lost to the Cincinnati Bengals in overtime 27–24.

[1][2] This would be the final season with long-time wide receiver Tyreek Hill, as he was traded to the Miami Dolphins on March 23, 2022.

Reid became the first coach in NFL history to win 100 games as a head coach with multiple teams as well as the first to lead multiple teams to four straight Conference Championships, previously doing so with the Eagles from the 2001 to 2004 seasons.

Tackle Eric Fisher was released[4] and fullback Anthony Sherman retired.

In the offseason, the Chiefs announced they would once again retire their live horse mascot Warpaint to continue with their commitment to stop using Native American imagery.

In Week 7, the Chiefs lost 3–27 to the Tennessee Titans, which is the fewest points scored in a game since Patrick Mahomes became the quarterback.

The Chiefs maintained a non-winning record until a week 9 victory over the Green Bay Packers.

After starting the season 3–4, the Chiefs won their ninth game in week 14 over the Las Vegas Raiders clinching their ninth consecutive winning season, one short of the franchise record of 10.

[9] In week 16, following a 36–10 victory over the Steelers and a loss by the Chargers, the Chiefs clinched their sixth consecutive AFC West division championship and their franchise record seventh straight playoff berth.

Kansas City defeated the Pittsburgh Steelers 42–21 in the Wild Card round of the 2021–22 NFL playoffs.

NFL Network began announcing their annual top 100 list on August 15, 2021.

Source unless otherwise noted[18] Below are players who were on the roster at the end of the 2020 season, but were either released or did not re-sign after their contract expired.

In addition the transactions below, the Chiefs placed running back Elijah McGuire on injured reserve.

*Marcus Kemp was initially released during roster cut-downs, but was signed to the practice squad.

The day after being signed to the practice squad, he was elevated to the active roster after linebacker Willie Gay was placed on injured reserve Below are transactions that occurred after the Chiefs first game through their final game.