The 29-year-old midfielder won three A-League titles with Brisbane Roar and an FFA Cup with Melbourne City.

He has signed a one-year deal after moving across from City, who on Friday announced they had signed Uruguayan, Adrian Luna on a two-year deal.

Brattan has joined fellow midfielders Alexander Baumjohann and Anthony Caceres in signing with Sydney, who have also acquired Socceroos central defender Ryan McGowan and New Zealand striker Kosta Barbarouses.

"Luke is a highly experienced player in this league and will strengthen our squad, providing exceptional competition for places,," Sydney FC coach Steve Corica said.

"Like many in our squad he is winner."

Brattan will begin training with Sydney on Saturday.

He could play in a pre-season game against NPL club St George FA next Tuesday and is set to travel to China for the Sky Blues match with French glamour side Paris St-Germain at the end of the month.

'"We have some fantastic quality in the squad who I am looking forward to playing alongside," Brattan said.

"Sydney FC is the benchmark in the A-League and my aim is to help push that to another level this season.

"I'm looking forward to winning more trophies with this incredible group of players and helping to take this club to our best ever finish in the AFC Champions League."