Competition Commissioner Margrethe Vestager said Google had used practices such as making manufacturers pre-install its search engine as the default in order to preserve its market dominance.
"The preliminary conclusions from our investigations is that these practices breach EU competition law," Vestager told a press conference, adding that Brussels believed that "Google has abused its dominant position"
She added: "We have found that Google pursues an overall strategy on mobile devices to protect and expand its dominant position in Internet search."
The EU in its charge sheet accused Google of obstructing innovation by giving unfair prominence to its own apps, especially its search engine, in deals with mobile manufacturers such as Samsung or Huawei.
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Google is also accused of restricting manufacturers from installing rival operating systems on their phones.
The Android operating system captures about 80 per cent of the world market for mobile phones, far ahead of its closest rival Apple.
In both cases, Google risks a fine of 10 percent of worldwide global sales for one year, which would amount to a USD 7.4 billion fine on the basis of 2015 revenues.
Google said it would work with the EU to show that consumers benefitted from Android.
"Android has helped foster a remarkable -- and, importantly, sustainable -- ecosystem, based on open-source software and open innovation," Kent Walker, Senior Vice President and General Counsel of Google, said in a statement.