The Commission's investigation comes down to whether Google has used the work of other people published online to build its own AI tools which it can profit from.
Its generative AI systems are capable of producing text, images and video in seconds, in response to simple text prompts.
Many firms can now do this - and they have used huge volumes of online web content to train their underlying systems.
But creatives have voiced concern their work may have formed the basis for big tech's AI products and outputs, at the expense of their own rights or livelihoods.
"A free and democratic society depends on diverse media, open access to information, and a vibrant creative landscape," said Commission executive vice-president Teresa Ribera.
She said AI was ushering in "remarkable innovation" and "many benefits for people and businesses" - but its growth should not come at the cost of the EU's values.
But the Commission's recent enforcement of its tough digital rules - which can see tech companies face huge fines if they found to be breaching them - has been met with outrage from US lawmakers.
Elon Musk's platform X axed the Commission's account for placing adverts on the site, after the EU brandished a €120m (£105m) fine over its blue verification badges.
