The NBA recordholder for triple-doubles reached the milestone late in a 122-110 victory.
The 36-year-old Westbrook finished with 12 points, 10 rebounds and 14 assists, and it took him until the final minutes to accomplish the feat.
With 1:28 left, Westbrook was one rebound shy of the triple-double when center Dario Saric missed a 3-pointer. Westbrook grabbed his only offensive rebound of the game.
With the Grizzlies still threatening, Saric knocked down a 3-pointer with 27.7 seconds left to preserve the Denver win.
Westbrook said he wasn't thanking Saric for the miss that led to the triple-double.
"I thank him for making the next one to close the game, which is the most important," he said.
Westbrook is 19 triple-doubles ahead of Hall of Famer Oscar Robertson, and 62 in front of Magic Johnson. His teammate -- Nikola Jokic -- is fourth with 136, followed by LeBron James at 117.
"It's a blessing," Westbrook said of reaching the milestone. "I'm truly grateful to be able to play the game (well enough) to do that. But I'm also appreciative of the ones who came before me."
Westbrook's teammates marveled at the accomplishment, not only the number of triple-doubles, but his longevity and the ability to reach such an accomplishment.
Julian Strawther, the second-year guard out of Gonzaga, said Westbrook is a celebrity everywhere they go.
"It's hard to put into words," Strawther said. "Two hundred triple-doubles is a lot. I don't even know if I've got 200 career games."
For Westbrook, the feat capped an ideal night.
"Anytime we win and I get them, I'm always grateful for that," Westbrook said. "It's my favorite time."