Foxe passed a series of fitness and medical tests this morning and with his signing approved by Football Federation Australia (FFA) this afternoon, he will play for the Sky Blues against Perth on Sunday.
"Hayden is an absolute professional," assistant coach Tony Popovic said. "He has represented the Socceroos and played in the English Premier League so he brings a wealth of knowledge to the group.
"We have had a few injuries in the last few weeks, especially in our defensive ranks, so Hayden provides us with another body and a lot of experience."
He also spent two seasons with Perth Glory between 2007 and 2009.
Meanwhile, defender Sebastian Ryall will miss six weeks after straining the medial ligaments in his left knee at training yesterday.
Sydney FC travel to Perth tomorrow evening ahead of their clash against the Glory on Sunday 10 January at ME Bank Stadium.