The 19-year-old impressed in spells last term, scoring in the Europa League and FA Cup.
Willock was used during Arsenal’s 2-1 win over Bayern Munich in the International Champions Cup this week.
The academy product is expected to play a more prominent role in Unai Emery’s plans this season.
And Ozil has backed his midfielder co-star to take his chance and become a ‘big player’ at Arsenal.
“He knows what he can do, so he is not arrogant on the pitch but he believes in himself,” he told Arsenal’s official website.
“Especially yesterday against Bayern Munich, against a big club, he shows his quality. We are happy to have him.
“He was strong last year as well.
“So of course, if you really work with the first team together always, you feel more comfortable and you believe in yourself more.
“I think this season, especially in the pre-season he shows his quality and I think he can help us this season.
“At the end of the day, those young players have quality.
“They show it every day in the training. If they stay healthy and believe in themselves, so I think he will be a big player.”
Emery has also been impressed with Willock since his arrival at the club.
“It’s all progress with him because last year he started with us in the pre-season,” he said after the Bayern clash.
“His performance today is very different to last year, maybe because he knows our idea and spirit better.
“He’s got a very big motivation and a very big ambition individually to make good performances, and he listens a lot to our idea. We are speaking a lot to him individually.
“I really, really think that he made one more step last year during the season and he finished it very well with us, playing 12 minutes in the final against Chelsea with a big performance.
“We now want him to take another step more in his capacity to be with us, with a big help in our performance and our idea.”