CJ McCollum added 22 points for the Blazers, who squandered a 17-point, fourth-quarter lead. Damian Lillard collected 18 points and eight assists for Portland, which ended a three-game losing streak.
Lillard opened the overtime with a 3-pointer, and Walker followed suit to make it 100-100.
Moe Harkless scored on a drive to pull the Blazers in front 102-100 with 3:09 remaining in the extra session.
Neither team scored again until McCollum made two free throws to extend Portland's lead to 104-100 with 1:09 left.
Harkless' follow dunk made it 106-100 with 37.4 seconds to go. Walker buried a 3-pointer to cut Charlotte's deficit to 106-103 with 30.2 seconds remaining, but McCollum sealed Portland's win on a floater with 12.2 seconds to play.
Walker scored 14 points in the second quarter as Charlotte rallied to get within 49-45 at halftime. Nurkic had 12 points and six rebounds for Portland at the break.
The Blazers used an 13-0 run to go ahead 73-58 midway through the third quarter. Portland carried a 79-65 advantage into the final period.
Charlotte cut Portland's lead to 81-71 early in the fourth quarter. Walker scored 15 consecutive points to pull the Hornets even at 95-95 with 2:54 remaining.
Nurkic sank a short jumper as the Blazers regained the lead at 97-95 with 2:35 to go.
Michael Kidd-Gilchrist evened it at 97-97 with a jumper with 1:50 to play.
Lillard missed a 30-footer with 52 seconds remaining. After a timeout, the Hornets turned the ball over, and Portland regained possession with 27.6 seconds on the clock. Lillard and McCollum both missed shots, and Charlotte called timeout with 1.6 ticks left. Howard's 20-footer was partially blocked by Nurkic, and it was on to overtime.
--Field Level Media