Burgess, who joined Bath last year after switching from league to union, was a surprise inclusion in Stuart Lancaster's World Cup squad and played at centre in England's damaging defeat to Wales as the hosts crashed out in the group stages.
"My decision to leave Bath and move back to Australia was for personal reasons, but it was also because I wanted to spend the rest of my career playing the game that's in my heart," Burgess wrote in a column for the Daily Mail.
"Rugby league is in my heart. I'm looking forward to getting back to Sydney, where I'll be with my family and playing for the Rabbitohs alongside my brothers again."
Burgess, who had two years remaining on his Bath contract, said he had converted to union to play inside centre -- the position he featured in during the recent World Cup.
Bath played Burgess as a flanker and the club's head coach Mike Ford had said the player was happier as a number six.
"I came to union to try to play at 12 but I ended up playing at six for Bath. I managed to get into the England training squad as a 12, even though I was playing as a flanker for my club," Burgess said.
"I could have just kept playing at six for Bath but I believe it would have taken about 18 months for me to break into the England team in that position -- and my contract is up in about 18 months.
"In sport, we have a very limited window in which to compete at the top level and I didn't want to see those 18 months go by without the same excitement and enthusiasm as the previous 12.
Burgess added that it was "tough" approaching Ford to ask to be released from his contract and apologised to the fans for leaving a "hole in the team".
He also accused ex-players, certain coaches not involved with England and sections of the media of having an "agenda" against England during the World Cup.
(Reporting by Simon Jennings in Bengaluru; Editing by John O'Brien)
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