Groves obtained a licence from the British Boxing Board of Control in April so that he could manage himself.
He claimed he "trusted no one" after defeat to Carl Froch in November.
But the 26-year-old has signed a deal with Sauerland before his WBA and IBF world title rematch against Froch at Wembley Stadium on 31 May.
Groves joins a stable of fighters that includes one of only two men to beat Froch - Mikkel Kessler.
"This is definitely a step in the right direction for me as I look to build my name not only across Europe but all around the world," said Groves.
"I feel that now I have the right team in place to help me achieve everything I need to in boxing."
Groves suffered the first loss of his career against Froch when referee Howard Foster controversially stopped their first fight in the ninth round.
World super-middleweight contender George Groves has signed a deal to be managed by Germany-based promoters Kalle and Nisse Sauerland.