She said: "In many areas we are only beginning to discover what openness means. Just how far its possible to go, just how much value we could unlock.
"With a truly open, universal platform we can deliver choice and competition; innovation and opportunity; freedom and democratic accountability."
Her comments come after Google's co-founder Sergey Brin warned that the openness of the internet was under threat from restrictive regimes as well as "walled gardens" such as Facebook and Apple.
Kroes also said that current copyright laws restrict "innovation and discovery", and "guarantee that Europeans miss out on great content".
She has been an outspoken critic of European copyright law in the past, calling it a tool to "punish and withhold."
Kroes began her speech by holding up a pair of handcuffs which had been sent to her by the Free Software Foundation, along with a letter asking if she was "with them on openness".
She said she wanted "everyone to operate across borders and be free of digital handcuffs," citing the use of the web in the Arab Spring, and calling for a "No Disconnect" principle in fledgling democracies.
"I am committed to ensuring 'No Disconnect' in countries that struggle for democracy. We must help such activists get around arbitrary disruptions to their basic freedoms," she said.