Portugal's carbon fund scheme will support projects installed in the ocean, such as tidal and wave technologies, as well as Principle Power's floating platform.
The EC said the funding abides by state aid rules of helping reach environmental targets without reducing competition.
Up to 50MW of renewable projects can be supported under Portugal's programme, 25MW of which will be taken up by WindFloat.
A 2MW prototype foundation was installed off the coast of Portugal in 2011 using a Vestas turbine.
Now the 25MW second phase of the project, using a larger turbine, will be able to receive state funding.
It is expected to be located 20 kilometres off the north Portugal coast. Water depths in the area reach up to 100 metres.
According to the EC, funding will be paid as part of a feed-in-tariff over 25 years. The project will also receive €30 million in funding under the European Union's NER 300 scheme.
The WindFloat platform was developed by the Principle Power consortium made up from EDP and Repsol.
The design is a semi-submersible platform consisting of three pillars with one holding the turbine tower.
Principle Power is also developing a full-scale 30MW project in the Pacific Ocean, off the coast of Oregon, northwest US. It is reported to use five Siemens 6MW turbines.
In May 2014, Principle Power was awarded $47 million by the US government's Department of Energy to fund the construction of the project.