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The 20-year-old was born in the Eastern Cape province, but his family moved to England when he was nine.
He had trained with Olympic silver medallist Louis Smith at Huntingdon Gym, but believes returning home will improve his Olympic prospects.
"It will open a lot of doors for me," the former British senior squad member told BBC Look East.
MacKenzie is a European junior team gold medallist with Britain and finished second in the vault and sixth in the all-around at last year's national championships.
He has also represented the senior squad at national level, but the prospect of competing for Team GB at major international events was being restricted by the country's world-class roster, with Smith, Max Whitlock, Sam Oldham, Kristian Thomas and Dan Keatings all rivals for selection.
"I would say I feel more South African than British," said MacKenzie, who was born in the coastal town of Jeffreys Bay.
"I won a competition for GB in South Africa in 2010. I remember standing up there on the podium with the British anthem playing and thought it didn't quite feel right.
"I've been here 11 years. I have a British passport, but I can't really forget I was born in Africa and my parents were. I can't forget my heritage that quickly."
MacKenzie has already made an impact on South African gymnastics, winning a Commonwealth Games qualifier in October to secure his place at Glasgow this summer and, under the British flag, finished highest at the 2013 national championships.
And he will compete in the Africa championships at the end of March, in the hope of making the qualifying scores needed to become the first South African artistic gymnast to go to the Olympics since 1956.
MacKenzie, who is now based at the Centurion Gymnastics Centre, intends to continue working with his Huntingdon coach Paul Hall and will send videos of his progress to receive tuition.
"I can really make a difference to gymnastics as a whole there and maybe kickstart something," he said.
"I can see what Louis Smith has done for the sport in this country and he's a great role model. I think it's definitely an achievable ambition to win the African champs, but there will be stiff competition."
British gymnast Cameron MacKenzie has chosen to represent South Africa in a bid to qualify for Rio 2016.