As the calendar made the turn from 2002 to 2003, the Boston Celtics franchise received new ownership. Boston Basketball Partners L.L.C., led by H. Irving Grousbeck, Wycliffe Grousbeck, Steve Pagliuca, Robert Epstein and David Epstein, completed the purchase of the team from Paul Gaston on December 31, 2002. Gaston had owned the team since 1992. The new ownership became the first local owners since 1964, when Walter Brown owned the legendary organization until his death.

For the third consecutive season, co-captains Paul Pierce (25.9 points per game) and Antoine Walker (20.1 points per game) average more than 20 points per outing and led the team to their second straight 40+-win season (44-38). It marked the first time the Boston Celtics have won 40 or more games in consecutive seasons in a decade (since 1991-92 and 1992-93 seasons). Despite the scoring heroics of both players, playing time added up as Walker logged 3,235 minutes (41.5 per game-4th highest in the NBA) and Pierce played in 3,096 minutes (an average of 39.2 per game). Pierce became just the second Boston Celtics player to record three straight 2,000-point seasons (2,048); Larry Bird recorded four straight from 1984-87. Pierce and Walker combined for 47.6% of the team's points in 2002-03 and both players were named the NBA's Eastern Conference Player of Week on two different occasions during the regular season. The co-captains were both named to the NBA Eastern Conference All-Star Team. Pierce ranked first in the NBA and broke the franchise record in free throws made and attempted, shooting 604-for-753 (80.2%) and he was a member of the United States 2002 World Championship team.

The Boston Celtics ranked 4th in the NBA in steals per game with an average of 8.78 per contest, while they took care of the basketball, ranking 7th in turnovers per game (13.99 per game). The Boston Celtics used the three-point line to their advantage as well, leading the NBA in three point field goals made and attempted, shooting 719-for-2, 155 (.33.4%). The 2002-03 Boston Celtics now hold the NBA record for three's attempted in a season, as they surpassed the Dallas Mavericks 2,039 treys attempted in the 1995-96 season.

The Green and White were one of sixteen teams to make the NBA Playoffs. The Boston Celtics defeated the Indiana Pacers in the First Round however were stopped, for the second consecutive year, by the New Jersey Nets in the Eastern Conference Semifinals.