"Android hasn't hurt competition, it's expanded it," said Kent Walker, general counsel of Google.
The US tech firm sent its reply on Thursday to anti-trust charges issued by the EU earlier this year over the smartphone platform.
The European Commission told the BBC it would carefully consider Google's response before making a decision.
Mr Walker said in a blog: "The response we filed today shows how the Android ecosystem carefully balances the interests of users, developers, hardware makers and mobile operators."
He said that more than 24,000 devices from over 1,300 brands ran on Android, enabling European developers to distribute their apps to over a billion people.
The European Commission sent a statement of objections to Google in April, alleging it had breached EU competition law.
Google faces a fine and could be required to change its practices if the EU rules against it.
The firm is accused of placing onerous requirements on companies using Android and giving unfair prominence to its own apps, especially its search engine, in deals with phone makers.
"No manufacturer is obliged to preload any Google apps on an Android phone," Google insisted.
It comes days after Google rejected the EU's objections in a separate case about how it displays shopping links in its search results.
Google has rejected EU allegations that it abused its market dominance of its Android mobile phone operating system.