The Australia youth international hailed the influence of the coaching staff at Everton in accelerating his impressive progress.
Ouzounidis was part of David Unsworth’s Under-23s squad that won a Premier League 2 and Premier League Cup double in 2018-19.
The 19-year-old is targeting more silverware next season as he set out his determination to develop all aspects of his game.
“I couldn’t be happier to sign a new deal and I’ll continue to work hard to be the best player I can be,” he told evertonfc.com.
“The facilities here are unbelievable and the coaches are brilliant. You’ve got every tool you need to progress, and my all-round game has improved a lot.
“Physically I’ve got a lot better, and technically, too, with the work every day on the training pitch.
“Last season was incredible for the team, winning the double. Hopefully we can win more trophies next season.
“Personally, I just want to play week in, week out, and improve as much as I can.”