The 20-year-old Young Socceroo from Sydney's North Shore will bolster the Sky Blues' defensive stocks and has signed on for the next two seasons after a successful stint with the Melbourne Victory.

 "I'm very grateful for the opportunity Melbourne gave me but I've always wanted to play for my home town, so I'm very happy to be back.

"I must confess when I was younger I used to go and watch (Sydney) and I was even in the Cove when they won the Grand Final against the Central Coast, so I was a fan before I went to Melbourne and it's exciting to be part of the team," said Ryall.

The Australian Institute of Sport graduate is looking forward to a successful season under incoming coach, Vitezslav Lavicka.

"I can't wait for the start of training. We have a good squad with a mix of youth and experience, a new coach and the club is working hard to create a winning culture so I'm sure we'll have a good year," he said.

Following Ryall's signing and the recent recruitment of Slovak international, Karol Kisel Sydney FC have a maximum of three places remaining in their senior squad.

The club will begin preparations for the forthcoming campaign when it starts pre-season training on April 27.