The Frenchman came off the bench for the Gunners to head home in the 85th minute, turning a 3-2 deficit into a 4-3 lead in the closing stages.
Arsenal spent £52million on Alexandre Lacazette to bolster their options up front this summer, and that already looks money well spent after the former Lyon man opened the scoring on his debut.
However, it was Giroud who once again saved the day for Arsenal, showing himself to be the ideal super-sub after excelling in that role for Wenger’s side last season.
Speaking afterwards, Giroud was asked again about his situation at the Emirates Stadium following speculation he could be on the move to Marseille or Everton.
‘I prefer to be on the pitch,’ the 30-year-old admitted in his post-match interview with Sky Sports. ‘As much as I can I try to help the team to reach our target.
‘Tonight we needed this win, everyone knows the importance of the first game for confidence.
‘I’m very pleased for the team tonight, hopefully we’re going to carry on.’
Arsenal didn’t get off the most convincing start against Leicester tonight, but Giroud more than proved his worth to the club by finding a winner after a real scare from the visitors.
Lacazette scored inside the first two minutes, before goals from Shinji Okazaki and Jamie Vardy gave the Foxes the lead. Danny Welbeck then made it 2-2 on the stroke of half time, but Vardy had given Leicester the lead once again in the 56th minute.
Aaron Ramsey equalised for Arsenal again in the 83rd minute before Giroud’s crucial touch just two minutes later completed the quick turnaround at the Emirates.