Kittel, who has been with the squad since 2011, struggled throughout the season with illness and injury and was unable to bring himself back to the form which has made him a superstar of the sport.
The 27-year-old was released with one year left on his existing contract and is now free to sign with a new team for 2016, rumoured to be Etixx-QuickStep.
“After my last setback, where I had to skip still more races, it became clear to me that I want to make a fresh start after a physically and mentally difficult year," Kittel said.
"When I shared this wish with the team, I was aware that it’s uncommon to release a rider from his contract before the end of the term. Therefore, I very much appreciate that Team Giant-Alpecin placed my personal wishes above the concern of losing a rider so late in the season and that it was receptive to my request to try and find a new team, which is something quite rare in the hard world of elite sports.
"I knew it would not be easy to make it happen this late in the season, but fortunately I expect to be able to find a suitable team, where I will race for the next few seasons. I am looking forward to it.”
Giant-Alpecin thanked Kittel for his five years of service, a period over which he established himself as the premier sprinter on the WorldTour, notably with eight Tour de France stage victories.
“We want to thank Marcel for the great contribution he has made to the team since 2011," Giant-Alpecin CEO Iwan Spekenbrink said.
"We really enjoyed his sprinting talent and the unforgettable moments we shared together, and we will continue to be proud of the sprints he will deliver in the future, as he will always be a ‘product of our school.’ We wish Marcel all the best in his future career.”