The 36-year-old Bafana Bafana international playmaker has spent 15 successful years with the Brazilians following his transfer from Vardos FC in 2011.
He has been a major part of the club's success over the years, claiming nine South African top-flight crowns and two Champions League titles.
Zwane has been used more sparingly by the club in the past few seasons, with injuries also playing a part, but he is still at the peak of his powers and has been selected by Bafana boss Hugo Broos as part of his final 26-man World Cup squad.
The experienced midfielder has now been rewarded with an extra year at Sundowns just as he was named the starting line-up for the international friendly draw with Nicaragua on Friday.
Sundowns posted online: "Our captain, Themba Zwane, has signed a new contract, extending his journey with Mamelodi Sundowns."
"You know how important Themba was to the national team before he was injured,” said Broos reflecting on the past season for Zwane.
"The moment he was injured it was difficult to find a replacement for him. We tried several things but were hoping one day Themba would be fit. And we were worried because at that age it is not easy to come back.
"I know Themba is not ready for 90 minutes at that (World Cup) level. But he is a good player and can help us for 45 minutes or for 60 minutes or maybe for less than that.
“Other players don't have the qualities he has. He has experience, he is intelligent in the game and he scores.”