Following eight years playing in the English Premiership, where he earned over 170 caps for Gloucester, the all-action flank is set to return to the country of his birth to strengthen the ranks in Cape Town.
The 29-year-old is renowned for his high work-rate and intensity on both sides of the ball, which are set to see him play a crucial role for his new team.
He joins the likes of Springboks Cobus Reinach and Ntuthuko Mchunu on a growing list of exciting new signings ahead of next season that also includes Blitzboks Tristan Leyds, Zain Davids and Quewin Nortje.
Director of Rugby John Dobson said that he is delighted to secure Ackermann's services for several reasons.
"Ruan is a proven performer who puts in the kind of hard work that our game model requires. Our fans can expect complete commitment from him for every minute he spends in our jersey.
"We are very excited to see the impact he will make here and I'm confident that he will become a firm favourite at DHL Stadium," he said.
Ackermann said that he cannot wait to get to Cape Town and link up with his new teammates.
"The support for rugby in Cape Town is second to none and there are obviously some incredible players and coaches there, so I am looking forward to what should be an exciting new journey for me and my family.
"I'm ready to give everything I have to the cause and make a positive contribution in any way I can as part of what will be a strong squad next season," he said.