The France international came on as a sub against Shakhtar having missed the last five months with injury.
Pep Guardiola was keen to give the left-back plenty of time to get back to full fitness and Gundogan believes the former Monaco star will kick on from here.
“It was great to see Benjamin back and it is a big boost for us,” said Ilkay.
GALLERY: Shakhtar 0-3 City | Match gallery
“Having him available again will be great for the team because we have missed him for the past five months and it’s also good for him.
“His fitness will improve as he gets some more game time and last night was an important step forward for him.
“We have lost a number of players recently, so having an important member of the squad return is just what we needed.
“We are competing in so many competitions and every player has a part to play so I’m really happy to see him return.”
On his own man-of-the match performance, the Germany star says he can do better and could have enjoyed an even better return than a goal and an assist.
He said: “I’m happy but I know I can still improve – maybe I could have scored a second goal and maybe provided a better assist for Raz but it was good to get a goal and also play the full 90 minutes because I think I needed that.
“It helps me, it helps the team and it helps everyone because we wanted to respond quickly.
“As you can imagine, the defeat at Norwich was very hard to take for us, that’s why beating Shakhtar was even more important and we can take this win into Saturday’s game against Watford which is already very close.
“We fly back to Manchester today, will arrive quite late and then we have less than 48 hours to prepare, but that’s why we have a strong squad.”