The Swedish midfielder came on for the final 15 minutes of Tuesday's 2-2 draw with the Swans and immediately made his physical presence felt at the heart of Arsenal's midfield.
Flamini was pleased to see his new team-mate settle in so quickly and thinks he could provide the Gunners with an important boost for the remainder of the season.
If he has some time to play I'm sure it will be very positive for our teamMathieu Flamini
"It was a great performance when he came in," Flamini told Arsenal Player. "I'm happy for him because it was his first game and we were all very happy to welcome him at Arsenal and in our team.
"He's a player with a lot of quality and if he has some time to play I'm sure it will be very positive for our team."
Flamini admits it has been a challenging week for the club but insists the team is determined to produce a reaction against Manchester City on Saturday.
"We know Manchester City is a strong team," he said. "We know they're a team who is hoping to win the Premier League but we want to prove we are a strong side and it will be important for us to react tomorrow with a victory.
"Of course it's been a difficult week, especially after the 6-0 at Chelsea and the draw but I think we have an interesting game tomorrow and it's good for us because we can prove to everyone that we can give a good reaction."