The 31-year-old, who has 19 Grand Tours stage wins including 14 on the Tour de France, terminated his contract with Team Katusha by mutual agreement in May to take a break from cycling.
He joined the Swiss outfit last year but never managed to reproduce the form that made him one of the world’s best sprinters, leading him to take some time out of cycling.
“The biggest question of the last few months was: Can I and do I want to continue to make the sacrifices needed to be a world-class athlete?,” Kittel said in a statement.
“And my answer is: No, I do not want that any more because I have always found the limitations on a top athlete as an increasing loss of quality of life.
“That is why I am very happy and proud that at this point in my life I can make the decision to follow my heart in a new direction.”
Kittel’s last significant victory came last year in the sixth stage of the Tirreno-Adriatico week-long race while his last win on the Tour de France was in 2017.