On the court Shaquille O'Neal scored 41 points as the Lakers came from behind in game six of the best-of-seven game series.
Twelve people were injured as some of the 10,000 fans who had gathered outside the Staples Centre arena in anticipation of a Lakers' win started rioting.
Two police cars were set on fire and two other vehicles wrecked as the revellers smashed windows, started bonfires and threw rocks and bottles at police.
The violence overshadowed the Lakers' 116-111 win over the Indiana Pacers to claim the NBA championship 4-2.
No arrests
Police said they had made no arrests after three hours of violence as fans were herded away from the Staples Centre.
Fans inside the stadium were kept inside as a precaution and the Pacers' team bus was not allowed to leave until two-and-a-half hours after game had ended.
Similar riots have also occurred recently in Denver and Chicago after football and basketball victories.
On the court Shaquille O'Neal scored 41
points as the Lakers came from behind in game six of the best-of-seven game series.
O'Neal, who was voted the Most Valuable Player of the Finals, won his first NBA title in his eighth year in the league.
Kobe Bryant finished with 26 points and Glen Rice added 16 points for the Lakers while Jalen Rose led Indiana with 29 points, Reggie Miller scored 25 and Dale Davis had 20 points.
The Lakers had not won the NBA title since Magic Johnson and Kareem Abdul-Jabbar led them to back-to-back championships in 1987 and 1988, their fourth and fifth titles of the decade.