After being knocked down, Leicester got right back up with a second Vardy goal to take the 3-2 lead. After Aaron Ramsey leveled in the 83rd minute, Giroud sealed the three points with a header inside two minutes on an evening of thrilling attacks gifted by fragile defending.
Alexandre Lacazette's arrival has bumped Giroud even further down the Arsenal pecking order, but having given the 30-year-old the chance to leave, Wenger was thrilled he chose to stay.
"Obviously I knew that I was going to have a chance so we tried to push", Giroudsaid. "In the end he made a decision to stay and it was one of the great days of the recent weeks for me. I know how important he is not only as a player but also in the group".
Arsenal were twice behind against Craig Shakespeare's side.
"I love the man and the player".
"This has happened to us the last three seasons here".
England striker Jamie Vardy stunned the Emirates with a neatly taken finish after an error from Xhaka, but Danny Welbeck levelled for Arsenal just before the break.
The future of Alexis Sanchez is unclear but Wenger has suggested he is prepared to keep the striker for a season and then let him leave on a free if he will not sign a £300,000-a-week contract.
Okazaki, who headed home by the far post from a short corner, was pleased he scored on opening night but was not about to get carried away.
"If you were a manager, you're on the bench when you're 3-2 down with 20 minutes to go, and you win 4-3, you're more happy than concerned", Wenger said.
Giroud, 30, started just 11 Premier League matches last season and scored 12 goals.
"We were quite good a year ago on corners".
The Germany worldwide appeared to handle the ball during the build to Aaron Ramsey's late equaliser.
Cech initially tipped over Riyad Mahrez's shot but the latter turned provider from the resulting corner. "We see players like Hector Bellerin, Alex Iwobi coming through, Reiss Nelson and Joe Willock have had a fantastic pre-season".
Giroud rescues Arsenal to seal 4-3 opening win vs Leicester
The £52 million signing became the first Arsenal player to score on his Premier League debut since Thomas Vermaelen in 2009. However, Arsenal and Liverpool could well have something to say about that, especially if the Wembley factor derails Spurs.
Raiders RB Marshawn Lynch sits during national anthem
Marshawn Lynch didn't play Saturday night, but he did make a statement in his return to an National Football League game field. Raiders coach Jack Del Rio was unaware of Lynch's intention to sit but said he spoke with the veteran rusher after the game.
No PSG contact over Sanchez - Wenger
Sanchez's last game was the Confederations Cup final for Chile on July 2 and he was given an extended summer break. The other big thing I will recommend for getting into soccer is there's always soccer one.