The 1964-65 NBA season was the Celtics' 19th season in the NBA. The Celtics finished the season by winning their eighth NBA Championship, defeating the Los Angeles Lakers in five games. The team was named one of the 10 greatest teams in NBA history. In addition five players were inducted into the hall of fame K.C. Jones, Sam Jones, Tom Heinsohn, Bill Russell, and John Havlicek, three of whom were selected as one of the NBA's 50 greatest players, Sam Jones, Havlicek, and Russell. Both Coach Auerbach and John Thompson were elected into the hall of fame as coaches.

The team's season roster is featured in the video games NBA 2K16 and NBA 2K17.

The 1965 NBA Draft took place on May 4, 1964.

The Celtics had a division semifinal bye.

(1) Boston Celtics vs. (3) Philadelphia 76ers: Celtics win series 4–3

Celtics win series 4–1