They missed out on having him available for their AFC Asian Champions League campaign but Coyne, who has been training with the Sky Blues for the last few weeks, has finally put pen to paper.

The former West Ham junior bolsters Sydney's defensive options for next season after the club also picked up Socceroo Michael Beauchamp from Melbourne Heart last month.

Coyne's signing has been a drawn out process for Sydney, who hoped to have the 30-year-old in their squad for the ACL only to be halted by a contractual dispute with Perth Glory at the time.

But with that issue resolved Coyne jumped at the chance to join the Sky Blues and feels he has plenty to offer the club.

"I have played against Sydney FC many times and all I wanted to do was beat them and they were games where you needed no motivation to rip in," he said.

"Now I will be on the other side and I will be giving it my all. I am naturally competitive and I will bring that to Sydney FC.

"I will play hard and give everything I've got. It is an exciting time for me."

Sydney coach Vitezslav Lavicka said Coyne's utility value would be a bonus for next season.

"He is versatile and can play in many positions which will give us options across the pitch," Lavicka said.

"He is much taller and bigger than people realise. I saw in the way he played in our friendly last week that he will be a good addition to the team.

"His positional play, ability in the air and his talking during the game was excellent. He did everything we asked of him and showed good character which is important to us here."

While Coyne comes into the club, there are a number of players likely to be leaving in the off-season with out-of-contract players Stephan Keller, Kofi Danning, Brendan Gan and Stuart Musialik all reportedly on the way out.

The Sky Blues play their final match of the ACL group stage against Kashima Antlers in Japan on Tuesday night.