The 2021 NBA playoffs was the postseason tournament of the National Basketball Association's 2020–21 season. With the COVID-19 pandemic impacting the NBA for the second consecutive year, the regular season was reduced to 72 games for each team and the start date of the playoffs was moved from its usual time in mid-April to May 22, 2021. It concluded with the 2021 NBA Finals in July, where the Milwaukee Bucks defeated the Phoenix Suns in six games after being down 0–2, marking their first championship since 1971.

Both the defending champion Los Angeles Lakers and the 2020 NBA Finals runner-up Miami Heat lost in the first round to the eventual finalists: the Phoenix Suns and the Milwaukee Bucks, respectively. The Suns advanced to their first NBA Finals since 1993 after winning the Western Conference finals against the Los Angeles Clippers in six games; the Bucks also won the Eastern Conference finals in six games, against the Atlanta Hawks to reach their first NBA Finals since 1974.

It was the first year the NBA used a 20-team playoff, with a two-stage system in both conferences, with 16 of the 20 teams advancing to the second stage. The first stage, the NBA play-in games, was a four-team playoff in each conference for the No. 7 to No. 10 seeds in each conference. In this format, the No. 7 and No. 8 teams need to win one game to advance to the second stage, with a double chance, while the No. 9 and No. 10 teams need to win two games to advance, eliminated by just one loss.

The NBA Board of Governors approved a format for the 2020–21 season to have a play-in tournament involving the teams that ranked 7th through 10th in each conference. The 7th-place team and 8th-place team participate in the double-chance game, with the winner advancing to the playoffs as the 7-seed. The loser then plays the winner of the elimination game between the 9th-place and 10th-place teams to determine the playoff's 8-seed. The NBA's regular playoff format would then proceed as normal. Furthermore, the winner of the match between the loser of the 7/8 game and the winner of the 9/10 game always plays on day 2 of the NBA playoffs to allow that team at least a day of rest.

Under the NBA's regular playoff format, the eight teams with the most wins in each conference qualified for the playoffs. The seedings were based on each team's record. Each conference's bracket was fixed; there was no reseeding. All rounds were best-of-seven series; the series ended when one team won four games, and that team advanced to the next round. All rounds, including the NBA Finals, were in a 2–2–1–1–1 format. In the conference playoffs, home court advantage went to the higher-seeded team (number one being the highest). Seeding was based on each team's regular season record within a conference; if two teams had the same record, standard tiebreaker rules were used. Conference seedings were ignored for the NBA Finals: Home court advantage went to the team with the better regular season record, and, if needed, ties were broken based on head-to-head record, followed by intra-conference record.

On April 25, 2021, the Utah Jazz became the first team to clinch a playoff spot. While noted in the below tables, division titles have no bearing on seeding.

Indiana (34–38) and Charlotte (33–39) also secured play-in berths but did not advance to the playoffs.

Golden State (39–33) and San Antonio (33–39) also secured play-in berths but did not advance to the playoffs.