| NBA playoffs | |
| Year: | 1978 |
| Season: | 1977–78 |
| Dates: | April 11–June 7, 1978 |
| Num Teams: | 12 |
| Winners: | Washington Bullets |
| Count: | 1 |
| Second: | Seattle SuperSonics |
| Semifinal1: | Denver Nuggets |
| Semifinal2: | Philadelphia 76ers |
| Prev Season: | 1977 |
| Next Season: | 1979 |
The 1978 NBA playoffs was the postseason tournament of the National Basketball Association's 1977-78 season. The tournament concluded with the Eastern Conference champion Washington Bullets defeating the Western Conference champion Seattle SuperSonics 4 games to 3 in the NBA Finals. Wes Unseld was named NBA Finals MVP. To date, it remains the only NBA title that the Bullets (since renamed the Wizards) have won.
It was the third NBA Finals appearance and first title for the Bullets, founded in 1961. The Sonics made the Finals for the first time in their 11-year existence. This would be the first of two straight meetings in the Finals between the Bullets and Sonics, with Seattle winning the title the next year.
This was the first time since the expansion of the playoff field to 10 teams in 1975 that neither conference champion had the benefit of a first-round bye by being one of the top two teams in the conference during the regular season. The 1979 Finals rematch between the Sonics and Bullets took place with both teams as the #1 seed in their respective conference.
The Denver Nuggets, one of the four former American Basketball Association teams to join the NBA the previous season, became the first of them to win an NBA playoff series, defeating the Milwaukee Bucks in a 7-game conference semifinal.