The 24-year-old became the Gunners' record signing after moving to north London from Real Madrid in the summer and has proved to be an instant hit at the Emirates Stadium.
Petit says that, while Arsenal still have some tough games ahead, he has been impressed with their early-season form and is hopeful that they can end their long wait for a trophy.
"There was a lot of pessimism around Arsenal at the start when they were beaten by Aston Villa in their first match," Petit was quoted as saying by the Sunday Mirror, "but they have recovered well since then and Ozil has been magnificent. He cost a lot of money but was the best bargain in the window.
|8/1||Arsenal are 8/1 with Bet365 to win the FA Cup
"With Aaron Ramsey looking back at his best after a bad injury, the signs are good. This could well be the season when they win a major trophy after a long wait. The young guns at the club will look up to the likes of Ozil and get confidence from being alongside him."
Arsenal top the early Premier League table but Petit acknowledges that they face a stiff examination of their title credentials in the coming weeks.
"They still have to face Chelsea, Manchester City, Liverpool and Manchester United. They will be big tests," he added, "and there is now the international break. It can sometimes be difficult to keep the same momentum you had before the break.
"But I have to say that so far they have been tremendous and playing some excellent football - football that is great to watch and some of the best in Europe."