The club confirmed in a statement on Wednesday afternoon that the 30-year old was joining the club for the 2021 and 2022 seasons.
Rabbitohs Head of Football Mark Ellison was thrilled by the acquisition of the ex-Panther.
“He is a high work rate winger who is one of the competition’s leading players in terms of kick return metres, as well as a renowned finisher,” Ellison told rabbitohs.com.au.
“More importantly he is a quality team and club man that inspires his teammates and brings energy to any team of which he is a part.
“He knows what our Club is about and respects the tradition and history of South Sydney, as well as the community that the Club represents.
“We reluctantly let Josh go in 2012 after playing a key role in our 2010 NYC Grand Final team and it is fantastic to have this opportunity to bring him back to South Sydney for 2021.
“That opportunity to bring him back would not be there if it wasn’t for Corey Allan moving on, another player who, like Josh in 2012, is moving on for opportunities elsewhere.
“We’re really excited to bringing a player of Josh’s ability and character back to our Club and we can’t wait to see him earn the right to pull on the Rabbitohs first grade jersey that eluded him a decade ago.”
Mansour has played 158 NRL games all for the Panthers since making his first-grade debut in 2012.
He has also represented the Australian Kangaroos, Lebanese Cedars and New South Wales in State of Origin.
It’s a homecoming of sorts for Mansour, who played 48 games for the Rabbitohs in the National Youth under 20s competition in 2009 and 2010.