The Frenchman supplied the assist for Lukas Podolski to equalise in the 16th minute after Younes Belhanda's opener before Gervinho made it 2-1 to the Gunners for the eventual victory.
Giroud admitted he was happy to return to the Stade de la Mosson to play in front of his old fans and was also satisfied with how he performed on the night.
"I tried not to really think about the context of the match," he told L'Equipe. "I was just so happy to come back here, even if I didn't score.
"I had a decisive assist in our first goal and I was quite satisfied with my own performance.
"We won and now we are in a good position. We remain undefeated and that is perfect for us."