Ackermann junior also moves to Gloucester
Ackermann, a member of the Super Rugby finalists, the Lions, departs South Africa after being overlooked for Springbok selection.
He will join the English Premiership outfit subject to visa clearance.
Ackermann has been an ever present in a strong and dominant back row for the Johannesburg based outfit, and moves to Kingsholm after helping the Lions reach the Final of this season's Super Rugby competition.
The son of incoming coach Johan Ackermann, and rated as one of the top up and coming back row talents in South Africa, Ruan has recently represented South Africa 'A' in their two-match series with the French Barbarians, ahead of the culmination of the Super Rugby season.
Ackermann made his first appearance for the Golden Lions in the 2015 Vodacom Cup, before being included in the Lions' Super Rugby squad for the 2016 season.
As well as this, Ackermann was called up to the Barbarians squad in the summer of 2016, playing against Samoa at the London Olympic Stadium.
Director of Rugby David Humphreys spoke of his excitement to see one of South Africa's most promising talents develop in the Premiership in Cherry and White.
"We are pleased that we have been able to bring Ruan on board, and he will definitely complement our existing resources in the back row, an area where we have real strength in depth and competition for places," Humphreys said.
"Johan of course knows all about the qualities that Ruan possesses, and Ruan himself knows exactly the high standards that Johan expects of his team and his players.
"Ruan has proved time and time again in Super Rugby this season how capable a player he is, taking on and matching some quality performers, and has also demonstrated his versatility in playing across the back row."
