The third-seeded Raonic, coming off a win at the Thailand Open on Sunday, hit 17 aces in the match.
"I'm playing better match by match," Raonic said. "I like this court. I've played four sets on this court so I have a good sense of how the ball reacts."
After coasting through the first set, the Thornhill, Ont., native took control in the sixth game of the second when he broke Chardy with a smash at the net to go up 4-2.
"I played well on return but I'm particularly happy with the serving," said Raonic. "I had a good percentage of first serves and I was able to to good things with the returns."
The 22-year-old, ranked 11th in the world, then held serve with three straight aces to take a 5-2 lead. Chardy fought back to make it 5-3 before Raonic closed out the match with another three aces in the final game.
"I was serving well and keeping up the pressure at the end of the first set," said Raonic. "From then on I was able to create the opportunities I needed to take the win."
Raonic will next face Slovakian Lukas Lacko, who beat qualifier Edouard Roger-Vasselin of France 7-5, 6-4.
"He doesn't have anything to lose," Raonic said. "As usual, I'll focus on my serve. He's a very dangerous and powerful player so I will have to play a tight, disciplined game."
Raonic, who is 39-17 this season, is trying to earn one of the last spots in the World Tour Finals in London next month.
In other matches, sixth-seeded Nicolas Almagro of Spain also advanced to the quarter-finals with a 6-4, 6-2 win over Horacio Zeballos of Argentina.
Defending champion and local favourite Kei Nishikori, who beat Raonic in last year's final, beat Spaniard Feliciano Lopez 7-6 (4), 6-0 and will face Almagro on Friday.
Top-seeded Juan Martin del Potro will play Alexandr Dolgopolov of Ukraine in the quarterfinals on Friday.
— With files from The Associated Press