Westbrook needed just five points to surpass the former Seattle SuperSonics great. He finished with 44 points in the Thunder's 131-122 loss to the New Orleans Pelicans.
The electric point guard now has 18,247 career points in his 11th season - all with the Thunder.
Westbrook added 14 rebounds and 11 assists to extend his triple-double streak to 11 games after breaking Wilt Chamberlain's NBA record of nine consecutive contests on Monday.
Golden State Warriors superstar Kevin Durant remains third on the list. He scored 17,566 points before leaving the franchise in 2016.