Grealish, who City signed for 100 million pounds this off-season, netted in the 22nd minute as Gabriel Jesus’ deflected cutback went in off the former Aston Villa man.
City turned on the style with a five-star display, crushing the Canaries with further goals from Aymeric Laporte, Raheem Sterling and Riyad Mahrez after the early Tim Krul own goal.
City boss Pep Guardiola was delighted with Grealish’s debut goal, believing he can become a regular scorer for the champions, having been more of a supplier at Villa last term, netted six times in the league.
“If he gets the mentality to score goals like Raheem, yeah (he can score more),” he said.
“When Raheem was here when I first arrived he didn’t have goals in his mind and we immediately changed his arrival.
“Today he scored because he arrives in the centre, he’s a machine there.
“He changed his mind and decided he was going to score. Jack has this mentality to score goals and win games as well.
“But if he has the Raheem mentality then he can do it, too.”
Guardiola was also delighted with Jesus’ display, claiming two assists for City.
“Im pleased with his performance; he was involved in three of our goals and is an Incredibly important player for us,” he said.
“He made an exceptional performance today, and I repeat, if he plays three minutes he plays the best three minutes for the club and everyone.”