The 26-year-old will restart his rugby league career in the 2016 season, and his deal should keep him with Souths until the end of the 2018 season.
“I want to thank everyone at England Rugby and Bath for some great memories over the last 12 months,” Burgess told the Rabbitohs’ official website.
“I must also thank Bath especially for granting my release to return home to my family who I have missed more than I could have imagined.
“I am also extremely excited to be joining back up with South Sydney. I cannot wait to get back into the Rabbitohs culture, full of great people and passionate members and supporters.
“I had a wonderful time in England and learned a lot about the game of rugby union as both a back and a forward, and I have definitely developed as an all-round player and athlete after that.
“I’m now very lucky to be given the chance to come back to Souths and serve this club and its members.
“I look forward to getting stuck into training with all the boys and working hard for the upcoming season.”
South Sydney coach Michael Maguire is delighted to see Burgess back in rugby league, and back with the Rabbitohs.
“I could not be happier to see Sam coming home to the Rabbitohs,” the former Wigan coach said.
“He had an enormously positive impact on our club, both on and off the field, throughout the five seasons he was here, and to be bringing back one of the game’s most dominant players is fantastic for not only our club, but the game itself.
“He will add starch to our forward pack, and he will bring his leadership qualities to the team as well.
“The next chapter is for him to return to the game he was born to play, and we’re over the moon that he is coming home to do that with his Rabbitohs family here at South Sydney.”