The penalty is almost double the previous record of 2.4 billion euros which the US tech company was ordered to pay past year over its online shopping search service. But it could add to trade tensions between Brussels and Washington.
"Android has created more choice for everyone, not less", it said in a statement.
Without rules around baseline compatibility, open-source platforms fragment, which hurts users, developers and phone makers, but Android's compatibility rules avoid this and help make it an attractive long-term proposition for everyone, Pichai said. "A vibrant ecosystem, rapid innovation, and lower prices are classic hallmarks of robust competition", a spokesman for the company said.
"The fine is based on the length of the infraction, but also on whether antitrust authorities believe there was an intention to commit the offence, and whether they excluded competitors or not", said another source close to the matter.
However, Google may challenge the ruling.
The European Commission said Google has to stop its behaviour within 90 days or face penalty payments of up to 5 percent of the average daily worldwide turnover of Alphabet, Google's parent company.
Google's Android system, which Google lets device makers use for free, runs about 80 percent of the world's smartphones, according to market research firm Strategy Analytics.
Competition Commissioner Margrethe Vestager previously fined Google 2.4bn euros ($2.8 billion) over a separate probe into its shopping comparison service - a ruling Google is in the process of appealing against.
The Commission says it is the "special responsibility" of bigger companies like Google to ensure other smaller players are able to compete fairly "on merit". Apple, Amazon and Facebook have also been penalized by European regulators.
"Any action by the European Union is akin to shutting the stable door after the horse has bolted", he said.
"The reality is that as long as they're delivering great utility to their consumers, consumers will still use those platforms".
Wednesday's ruling caps an investigation that goes back at least three years.
Kerber defeats Williams to win Wimbledon
She had some words for all of her fellow mothers: "To all the moms out there, I was playing out there for you today and I tried". In a role reversal from her wedding - at which Williams was a guest in May - Markle is watching her friend from the royal box.
Duck Boat Accident Kills 17
The accident happened on Table Rock Lake in Branson, a tourist area famous for country music shows and other entertainment. Critics argued that part of the problem is that too many agencies regulate the boats with varying safety requirements.
Walmart is Reportedly Working on a Netflix Like Streaming Service
It certainly has the cash reserves, having generated $17 billion in cash a year ago . Of 3,729 Brits polled by Ofcom, 46% said they never use such services.