The ceremony was held in Berlin and featured a performance from the boyband, as well as appearances from Adele and Bruno Mars.
The 'Kidz' singers thanked the German music industry and fans for their support.
"Germany is incredibly good to us," announced Robbie Williams when collecting the award.
Bon Jovi and Hurts were also nominated for the award, which takes into consideration German record sales over the past year.
Other winners included Eminem for 'Best Hip-Hop Artist' and Amy MacDonald for 'Best International Rock-Pop Artist'.