The 27-year old joins from Red Star Belgrade and will link up with his new team mates at training next week.
 
Petkovic has played in some of Europe’s biggest leagues, including Germany’s Bundesliga during a three year stint with Eintracht Frankfurt, and was in the Hapoel Tel Aviv side which played in last season’s Europa League.
 
The former Serbian under 21 international has represented his country 34 times, helping to keep Italian striker Mario Balotelli quiet during the 2009 European under 21 Championships, and has also played in Turkey and Russia.
 
“Nikola’s signing is an excellent piece of business for Sydney FC and completes our squad,” said Farina. “He can play anywhere across the back four and will give our defence strength and depth.
 
“I am expecting big things from him this season and believe he will have a big influence on the squad.”
 
Petkovic will be available for the  season opener when Sydney FC meet Newcastle Jets at Allianz Stadium.
 
“This is an exciting new challenge for me and it’s a privilege to be signing for Australia’s biggest and most recognisable football club,” said Petkovic.
 
“Sydney FC has a great reputation and I can’t wait to wear the Sky Blue jersey and meet the members.
 
“The opening game at Allianz Stadium is going to be huge and is one I’m very much looking forward to.”