The 24-year-old left-back, who signed from Wolverhampton Wanderers earlier this month on a five-year deal, impressed both fans and manager Pep Guardiola with an eye-catching display.
Guardiola, who made wholesale changes from the side that faced Wydad in their previous match, was particularly pleased with Ait-Nouri's contribution.
"Wow. He had to defend a back four, then make a back five. He played really, really good. Not for the first time," said Guardiola.
"It was his first game but he has played in the Premier League for many years, he can help us play in that role outside but then had to play as a holding midfielder and go into the pockets. He moves really well into the spaces.
"He is intelligent and clear to defend and take the ball. He is so clever in the final third, taking the right decisions to create more spaces. Really pleased for the game he played."
Ait-Nouri joined City after a strong season with Wolves, where he made 37 Premier League appearances, scoring four goals and providing seven assists.
His confident showing in his first start for City was complemented by Ilkay Gündogan's masterclass performance, with the German midfielder deservedly earning man of the match honours.
With the emphatic win, City now sit second in their group. The focus quickly shifts to their crucial fixture against Juventus on Thursday.
Victory will not only secure progression to the knockout stage but also help them avoid tournament giants Real Madrid in the last 16.
Failing to top the group could see City face Madrid as early as Tuesday, 1 July, in Miami - a daunting prospect Guardiola's men will be eager to avoid.
Erling Haaland has given a confident update on his Manchester City future, stressing his commitment to the club's long-term project while accepting the uncertainty around Pep Guardiola's contract beyond 2027.
Kylian Mbappe's race to be fit has taken another hit, with the French forward facing a serious battle to return for Real Madrid after remaining unused in their 2-1 defeat to Manchester City at the Bernabeu.
Manchester City boosted their push for a top-eight finish in the Champions League league phase with a 2-1 comeback victory over Real Madrid at the Bernabeu.
Xabi Alonso has demanded an immediate response from Real Madrid after they were stunned at home by Celta Vigo, admitting his side were "angry" and determined to put things right when they face Manchester City in the Champions League.
