Although financial terms of the deal were not disclosed it is understood that Das Werk is paying£5-7m for the stake.
The deal marks the German group's first foray into the UK market, but Das Werk's chief financial officer, Joachim Sturmes, stressed that while further acquisitions could not be ruled out, the company was not 'on a UK shopping spree'.
Glassworks managing director Hector Macleod said: 'This union will enable us to take our skills to a wider audience.'
The deal, which is expected to be completed by 1 January next year, will see Glassworks become an integral part of Das Werk's post-production network, which includes 11 facilities in Germany, one in Zurich plus Spanish post-production group En Efecto with offices in Barcelona, Montreal and Seoul.
Das Werk plans to produce feature-length animations and TV series in which Glassworks is expected to play an integral role. Macleod has long intended to focus part of Glasswork's core business on digital content production and said an independent animation arm of Glassworks was planned for next year.
Das Werk also intends to set up a London division of Crater Software, the R&D and software distribution subsidiary originally set up by En Efecto in Barcelona. Glassworks' R&D outfit, which has already licensed FurShader to Softimage, is expected to become the base for Crater Software London.
Das Werk said it was also planning further European acquisitions in France and Italy as well as a joint-venture with a facility in Rotterdam.
Mikros Image in Paris and Blue Gold in Milan are earmarked, particularly as both are members of the MAX European post-production alliance. En Efecto was an original member of the MAX alliance, meaning Das Werk now holds a total 33.3 per cent shareholding. Brussels-based facility ACE is also a member, while Glassworks becomes the first UK outpost for the European joint-venture.