The French midfielder re-signed for the Emirates Stadium outfit in August and made his second debut for the club in the north London derby win over Tottenham last Sunday.
And even though he spent five years in Serie A after leaving Arsenal in 2008, the 29-year-old believes the club is similar to how it was in his first period there.
"I really have the sensation of being back home," he told Arsenal's official website.
"I have heard it a lot (that it is like I have never been away). I feel like I never left.
"There are players I played with before, and even staff, there are a lot of people still here that I knew before and the (relationship) with the fans was just amazing."
The victory over Tottenham came after Arsenal booked their place in the UEFA Champions League group stages by overcoming Fenerbahce in the play-off round.
Manager Arsene Wenger added Germany international playermaker Mesut Ozil to his squad for a club-record fee on transfer deadline day, and Flamini believes the atmosphere within the club is positive.
"The quality is very high in this team and at this club," he continued.
"That is the most important thing, to have players of quality because that makes a difference.
"The team spirit is also very good, and we saw on Sunday that everyone was helping each other on the pitch. That makes a difference in the big games."
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