Ghoochannejhad joined the Cypriot club ahead of the 2018-2019 campaign and scored two goals in 15 games before his loan move.
The 31-year-old retired from international duty last year, having scored 17 goals in 44 appearances for Iran, including at the 2014 World Cup.
"I'm excited to be joining Sydney FC and looking forward to the challenge of the A-League and AFC Champions League," Ghoochannejhad said.
"To be joining Australia's most successful club is a fantastic move for me, and to test myself against the best in Australia and Asia will be an unbelievable experience.
"Sydney FC's record in recent times is phenomenal and they have some fantastic players.
"I can't wait to link up with my new team-mates, help them add to their success and bring more trophies to the club."
With 11 games to go in the regular season, the Sky Blues are third in the A-League table, five points behind leader Perth Glory.
The signing of Ghoochannejhad – who has previously played for the likes of Charlton Athletic and Heerenveen – is also a boost for Sydney ahead of the AFC Champions League, in which they will face Kawasaki Frontale, Shanghai SIPG and a play-off winner in Group H.