on november 25, 2018, dinwiddie scored 31 points in a 127–125 loss to the philadelphia 76ers. on december 12, he scored a career-high 39 points in a 127–124 win over the 76ers. the following day, he signed a reported three-year, $34 million contract extension with the nets. on december 26, he had 37 points and 11 assists off the bench in a 134–132 double-overtime win over the charlotte hornets. it was his third 30-point game off the bench, matching the franchise record set by clifford t. robinson in 1980–81. on january 16, 2019, he scored 25 of his 33 points in the fourth quarter and overtime of the nets' 145–142 win over the houston rockets. on january 23, he scored a game-high 29 points in a 114–110 win over the orlando magic, thus scoring at least 25 points off the bench in 10 games, matching a franchise single-season record—bubbles hawkins set the mark during the nets' inaugural nba season in 1976–77. two days later, it was revealed that a right thumb injury that he had originally hurt roughly two months earlier and had gotten progressively worse would require surgery, having suffered torn ligaments. he underwent surgery on january 28. he returned to action on march 1 after missing 14 games, scoring 15 points off the bench in a 123–112 loss to the hornets. with 28 points against the cavaliers on march 6, dinwiddie had his 14th 20-point game off the bench to set a nets single-season record—darryl dawkins, purvis short and orlando woolridge all had 13. with 23 points against the hawks on march 9, dinwiddie surpassed armen gilliam in 1993–94 with the most single-season points in a reserve role.