The South African cut his teeth at the Bulls before heading North to pastures new in England with Saracens in 2021. The nippy No.9 earned 123 caps for the English giants, scoring a try in the 2023 Premireship final to help them secure the title.
Now, the six-time Springbok returns to the republic. He replaces World Cup winner Grant Williams, who is headed to Japan.
"Looking at the last five years as a whole, it's not always been easy, but it has been so worth it," said the 30-year-old in a statement.
"Being a centurion for this great club, winning the PREM and captaining this side on the odd occasion is something I am very proud of.
"For me and my family, Saracens will always have a special place in our hearts. I am leaving here with no regrets and peace in my heart, knowing that I gave this place and the people everything I had while I was here.
"I want to thank my wife for sacrificing so much so I can play for this club. This will always be Olivia's first home, and the first team she saw her dad play for. Thank you!"
Van Zyl joins Bradley Davids, Jaden Hendrikse and Canada international Ross Braude as the other scrumhalves at the Durban Franchise.