The France ball-winner, 29, left The Emirates for AC Milan in 2008 but, having been released on a free transfer by the San Siro giants at the end of last season, began training with the Gunners over the summer.
He then impressed manager Arsene Wenger with his determination and improved his fitness levels, earning a contract in late August and coming off the bench in the 1-0 win over Tottenham on September 1 to a rapturous reception.
Flamini told Sky Sports: "He (Wenger) saw that I was fit again and in really good condition.
"For everyone, (the Spurs game) was a special game but for me it was something more because it was obviously going to be my first game in front of our fans at The Emirates.
"I was a bit nervous, to be honest. I probably warmed up for five seconds and then I had to come in. It was a great sensation and a great communion with the fans.
"It was a great moment. I don't think I will ever forget it."