The 1989–90 NBA season was the 44th season of the National Basketball Association. The season ended with the Detroit Pistons winning their second NBA Championship, beating the Portland Trail Blazers 4 games to 1 in the NBA Finals.
* The Minnesota Timberwolves and the Orlando Magic entered the NBA as the league's 26th and 27th franchises. The Timberwolves played their preseason schedule at the Met Center in the Minneapolis suburb of Bloomington home of the NHL's Minnesota North Stars. They played their regular season schedule at the Hubert H. Humphrey Metrodome, former home of the NFL's Minnesota Vikings and MLB's Minnesota Twins. They would move to smaller-capacity Target Center for the 1990–91 season. The Magic would play at Orlando Arena (later known as TD Waterhouse Centre and Amway Arena) for the next 21 years.
* The NBA All-Star Weekend was in Miami Arena in Miami. In the 1990 NBA All-Star Game, the East defeated the West 130–113. Magic Johnson of the Los Angeles Lakers took home the game's MVP award. Dominique Wilkins of the Atlanta Hawks edged out Kenny Smith of the Sacramento Kings to win the Slam Dunk Contest.
* The Charlotte Hornets were aligned in the Midwest Division in the Western Conference. Charlotte would be aligned in the Central Division for good starting the next year. The league had placed the four new teams in different divisions to spread them out over their first few seasons.
* The NBA on CBS concluded its 17-year run (dating back to 1973). The program was succeeded by The NBA on NBC.
* The NBA adopted the FIBA rule that game clocks register tenths of seconds in the final minute of a quarter. This rule turns controversial during the season because of clock calibration problems in many venues; following a January 15, 1990, game at Madison Square Garden between the New York Knicks and the Chicago Bulls where Trent Tucker sank a three-point basket with the ball put in play with one-tenth of a second remaining, the NBA mandated clock calibration and prohibited any shot made when the ball is put in play with less than three-tenths of a second remaining from counting unless it is a dunk or a tip-in. The Trent Tucker Rule would be established the following year as a result of this incident.
* All three Texas-based teams made the playoffs. This would not happen again until 2004.
* This was the last of nine consecutive seasons in which the Lakers finished as the No. 1 seed in the Western Conference. They would not return there until 2000.
* Long-time Boston Celtics announcer Johnny Most retired after 37 years behind the microphone. Most was best known for his call of "Havlicek stole the ball!!" in the 1965 Eastern Division Finals between the Celtics and the Sixers.
* The Philadelphia 76ers won their first Atlantic Division title since the 1982–83 championship season, and the first in the post-Julius Erving era. They lost to the Bulls in the second round of the playoffs.
* Several players from Eastern Bloc countries in Europe made an impact in the NBA. Yugoslavia's Vlade Divac and Dražen Petrović, and the Soviet Union's Šarūnas Marčiulionis and Alexander Volkov were among the pioneering players from Eastern Europe who made the jump to the NBA.
* On March 28, 1990, near the end of the 1989–90 season, the Cleveland Cavaliers faced their new nemesis Michael Jordan. Needing the victory to clinch a playoff berth, Jordan set his career high with 69 points in an overtime win and putting a dent in the Cavaliers' playoff plans.