The 1985 NBA World Championship Series was the championship round of the 1984–85 NBA season.

The Boston Celtics were looking to repeat as NBA Champions for the first time since the 1968–69. The Celtics had homecourt advantage for the second year in a row as they finished the regular season with a 63-19 record while the Los Angeles Lakers compiled a 62-20 record. The Lakers looked to bounce back from the previous year's painful loss to the Celtics in the championship series, and were still seeking to beat Boston for the first time ever in NBA Finals history. Also for the first time, the Finals went to a 2-3-2 format with Games 1 and 2 in Boston while the next three games were in Los Angeles. The final two games of the series would be played in Boston, if required. This change of format came after David Stern had a conversation with Celtics legend Red Auerbach in 1984, who didn't like the frequent traveling between games.

The Los Angeles Lakers defeated the Celtics four games to two to defeat the Celtics for the first time in Laker history in the NBA Finals.

The NBA Finals is the championship series of the NBA. The series was named the NBA World Championship Series until 1986.

The series is played between the winners of Western Conference Finals and Eastern Conference Finals. At the conclusion of the championship round, the winners of the NBA Finals are awarded the Larry O'Brien Championship Trophy. (Winners from 1946 to 1977 received the Walter A. Brown Trophy) The NBA Finals has been played at the conclusion of every NBA and BAA season in history, the first being held in 1947.

Since 1985, the winner of the NBA Finals has been determined through a 2–3–2 format. The first two and the last two games of the series are played at the arena of the team who earned home court advantage by having the better record during the regular season.

During the first decade the Minneapolis Lakers had the first NBA dynasty, winning 5 championships in 6 years under Hall of Fame head coach John Kundla. The team also featured George Mikan, one of the greatest players in the history of the NBA. Franchises which had previously been in the National Basketball League tended to dominate, especially the Minneapolis Lakers.