Degenkolb won Paris-Roubaix and Milan-San Remo in 2015 and joins Lotto Soudal after spending three seasons with Trek-Segafredo.
"The talks with Lotto Soudal have revealed that there are many similarities between the team's goals and mine," said Degenkolb. "It makes sense that a Belgian team with a long history in cycling wants to excel during the Classics.
"That will be the aim for the first part of the season. In addition, I'm not slow at the finish, especially after a tough race. Of course, I also look forward to working with Caleb Ewan, who will undoubtedly be our number-one sprinter for his specific goals. But with my experience, I can provide added value for him and for Lotto Soudal."
Degenkolb also talked about an intriguing dynamic in the April Classics with Gilbert. With seven Monument victories among the pair, Lotto Soudal appear to be making a concerted push to succeed next spring.
"I'm already look forward to preparing the 2020 season and to getting to know everybody," Degenkolb said.
"Me and Philippe Gilbert can make a complementary duo. We get along really well, I admire him as one of the best Classics riders and with his style of racing, opportunities will come along for all of us."
Team manager Marc Sergeant welcomed the arrival of Degenkolb, adding that the German was willing to "commit" to working for Caleb Ewan.
"With John Degenkolb and Philippe Gilbert, we managed to add two great riders to our team," Sergeant said.
"John is fast after a hard race, which makes a big difference if you go to the finish with, for example twenty riders. I hope that we will get to see the best Degenkolb the coming years and I am convinced that he is capable of doing so.
"He indicated that he wants to recognize and try to take opportunities, we will for sure be able to define some nice objectives, he is flexible in terms of his race schedule and he definitely wants to commit himself to Caleb Ewan.
"The fact that we are able to get a German rider on board, is a nice bonus for our partner Soudal, for whom the German market is very important."