Major TV series including Game of Thrones, True Blood and Boardwalk Empire are now available to buy and stream through Google Play.
Google has also made Girls and Veep available through the store, as well as back catalogue series The Wire, The Sopranos and Band of Brothers, which are due to come later.
"We are delighted to bring our wide range of programming to Google Play in the UK, and expand on our existing relationship in the US," said HBO's Colin Smith.
"This is an exciting time for HBO in the digital space and we can't wait to work with Google over the coming weeks and months to deliver all of our series and films to their platform, including a host of new and returning HBO shows throughout 2014."
The third season of Game of Thrones costs £18.49 for all ten episodes, or £1.89 for a single episode in standard definition, while HD copies cost £24.99 and £2.49 respectively.
Web rival Blinkbox secured exclusive rights to the hit fantasy series in July, but Google will be celebrating a victory against iTunes, which does not currently offer the show.
In August Google Play added top shows from the BBC, ABC and Sony Pictures Entertainment to its roster.
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