The 1981 NBA Playoffs was the postseason tournament which followed National Basketball Association's 1980-81 season. The tournament concluded with the Eastern Conference champion Boston Celtics defeating the Western Conference champion Houston Rockets 4 games to 2 in the NBA Finals. Cedric Maxwell was named NBA Finals MVP.

The playoffs are notable for being the only time to date that a team with a losing record ever advanced to the NBA Finals, as the Rockets won their first Western Conference Title despite having a 40-42 record (the other Western Conference Finalist, the Kings, was also 40-42).

The Kings' playoff series victories over the Blazers and Suns were the last for the franchise in Kansas City. The franchise's last playoff series in Kansas City was a 3-game sweep in the first round in 1984 by the Lakers. The team moved to Sacramento after the 1984-85 season and didn't win a playoff series representing northern California until 2001.

The Pacers became the last former ABA team to make their postseason debut, though 2 straight losses to the 76ers ended their first playoff run.

The National Basketball Association (NBA) Playoffs is a best-of-seven elimination tournament among sixteen teams in the Eastern Conference and Western Conference (called Divisions, pre-1970), ultimately deciding the final four teams who will play in the NBA Conference Finals.

The NBA announced the current revised playoff seeding system on August 3, 2006. Following the NBA regular season, eight teams in each conference qualify for the playoffs and are seeded one to eight.

The team that has the best record in each of the three divisions in each conference is declared division champion. The three champions, and another team in the conference with the best record, are seeded one through four by their records. This guarantees that the division champions will be no lower than fourth seed, and also ensures that a conference's two best teams (by record) are ranked as the top two. However, because the NBA does not re-seed its teams and because home court advantage goes to the team with the better record, not the better seeding, division winners are guaranteed no better than a de-facto five seed, as their 4th seeding does not guarantee home court advantage in the first round, and after the first round the 4 vs 5 winner will play the same teams as the loser would have played had they won the first round. This will continue throughout the remainder of the playoffs and to the finals until the 4 vs 5 winner loses a playoff round or wins the championship. Of the remaining eleven conference teams, the four with the best records are seeded fifth through eighth based on their record.