Westbrook missed the preseason and the first two regular season games after having a procedure in September 2018 to deal with inflammation in his right knee. In his season debut for the Thunder on October 21, Westbrook had 32 points, 12 rebounds and eight assists in 35 minutes in a 131–120 loss to the Sacramento Kings. On November 19, he returned to the line-up after missing five games with a left ankle sprain and had 29 points and 13 assists in a 117–113 loss to the Kings. On November 21, he recorded his first triple-double of the season with 11 points, 13 assists and 11 rebounds in a 123–95 win over the Golden State Warriors. On November 28, he recorded his third triple-double of the season with 23 points, 19 rebounds and 15 assists in a 100–83 win over the Cleveland Cavaliers. He moved into a tie for third place on the NBA list for triple-doubles, with the 107th of his career matching Jason Kidd's total. He moved into sole position of third on December 5, recording his 108th career triple-double with 21 points, 17 assists and 15 rebounds in a 114–112 win over the Brooklyn Nets. On December 28, he scored 40 points in a 118–102 win over the Phoenix Suns. On December 31, he had 32 points, 11 rebounds and 11 assists for his 10th triple-double of the season in a 122–102 win over the Dallas Mavericks. On January 10, he recorded a career-high 24 assists to go with 24 points and 13 rebounds in a 154–147 double-overtime loss to the San Antonio Spurs. On January 31, he received his eighth career All-Star selection by being named a Western Conference reserve. On February 5, he had his seventh straight triple-double with 16 points, 16 assists and 15 rebounds in a 132–122 win over the Orlando Magic. He matched the longest triple-double streak of his career with his 20th of the season and No. 124 overall. On February 7, he had 15 points, 15 assists and 13 rebounds in a 117–95 win over the Memphis Grizzlies, thus the longest triple-double streak of his career and sitting one short of Wilt Chamberlain's NBA record of nine straight set in 1968. On February 9, in a 117–112 win over the Houston Rockets, Westbrook had 21 points, 11 assists and 12 rebounds to match Chamberlain's record streak. On February 11, Westbrook broke Chamberlain's record after tallying 21 points, 14 rebounds and 11 assists in a 120–111 win over the Portland Trail Blazers. On February 14, he recorded 44 points, 14 rebounds and 11 assists in a 131–122 loss to the New Orleans Pelicans. In addition to increasing his triple-double streak, Westbrook surpassed Gary Payton (18,207 points) as the career scoring leader in franchise history. His streak of 11 consecutive games with a triple-double ended in the first game after the All-Star break, as he recorded 43 points, 15 rebounds and eight assists in a 148–147 double-overtime win over the Utah Jazz. On April 2, Westbrook had 20 points, 20 rebounds and 21 assists in a 119–103 win over the Los Angeles Lakers. He became the second player in NBA history to record 20 points, 20 rebounds, and 20 assists in a single game; the only other coming from Chamberlain in 1968. Westbrook also tied Chamberlain for second all time in 15-point, 15-rebound, 15-assist games with eight. On April 5, his performance of 19 points, 15 assists, and eight rebounds in a 123–110 win against the Detroit Pistons ensured he would clinch his third consecutive season averaging a triple-double—the first time in NBA history. The game also secured his position as league leader in assists per game for the third consecutive season, achieved only by six other players in NBA history. In the Thunder's regular-season finale on April 10 against the Milwaukee Bucks, Westbrook posted his 34th triple-double of the season to reach 138 for his career, tying Magic Johnson for second place on the career triple-double list. The Thunder went on to lose in five games to the Trail Blazers in the first round of the playoffs, with Westbrook recording two triple-doubles during the series.