The move follows Sky's acquisition of WiFi network company The Cloud in January 2011 and is part of the satellite broadcaster's strategy to compete with BT, which currently operates the UK's largest estate of WiFi hotspots.
Sky Cloud WiFi will be offered at venues through which an estimated 4m people pass every day, including outlets of Pizza Express, Caffè Nero, Eat, Pret A Manger, JD Wetherspoons and Wagamama, as well as First Great Western trains.
More than 4,000 hotspots have been added to The Cloud's network since January 1, as part of a major rollout programme. The company has also announced new deals with Network Rail and King's Cross Urban Zone.
WiFi hotspots from The Cloud will be accessible at no extra charge to all Sky Broadband Unlimited, Sky Fibre Unlimited and Sky Connect customers, enabling them to access unlimited internet on smartphones, laptops and tablets. It will also enable people with 3G mobile data plans to save on their monthly allowances by switching to WiFi.
Recent research by Sky suggests that its broadband customers are more likely than the average to own smartphones and tablets, while around a third of Sky homes regularly watch video content on their mobile devices, including the Sky Go multiplatform service.
Accompanying the Sky Cloud WiFi launch in mid-April, Sky will introduce a companion app for Apple iOS and Android devices, allowing people to automatically connect their device to the internet at different locations without having to repeatedly log in.
Customers can register up to six devices per Sky Broadband household to the WiFi service, and there are no data allowances or usage limits.
"Whether it's to go on Facebook, watch favourite TV shows with Sky Go, catch up on the news or send an email, our customers can now enjoy high quality, reliable and unlimited broadband whether it's at home or when out and about," said Lyssa McGowan, the director of communication products at Sky
"WiFi Hotspots from The Cloud now gives millions of Sky customers quick and easy one-touch access whenever they want to be online. And by ensuring our hotspots are located where our customers need them most, they know they'll never be far from a high speed connection.
"With a one-off registration process, they'll automatically connect to the network, which takes all the usual hassle out of connecting to WiFi."
Separately, The Cloud has agreed a new deal with Network Rail to upgrade WiFi services at nine UK stations and roll out hotspots at a further seven.
The seven new stations getting The Cloud's WiFi are: Leeds, Liverpool Lime Street, Manchester Piccadilly, Glasgow Central, London Cannon Street, London Euston and London Bridge.
The stations being upgrade are Edinburgh Waverley, London Liverpool Street, London Fenchurch Street, London Charing Cross, London Waterloo, London Victoria, Gatwick Airport, London Paddington and London King's Cross.
"As Network Rail is investing in upgrading its iconic rail stations so we too are making significant investment to deliver state of the art WiFi for its customers all across the UK," said Vince Russell, managing director of The Cloud.
"Whether it's delivering real time travel info to hurrying commuters or allowing people relaxing at the station to catch up on the latest news, emails and social media, this service will enhance the quality of their visit."
The Cloud has agreed another deal with King's Cross Urban Zone, involving the creation of what is claimed to be London's largest WiFi-enabled outdoor area on the 67-acre site.
Alison Ruck, the head of IT at King's Cross, said that providing free, unlimited WiFi at the Urban Zone is a "vital ingredient" in encouraging people to use the space.
She added: "The internet is becoming a basic requirement in our lives which is why at King's Cross, whether people are walking up King's Boulevard or sitting in Granary Square, they will be able to stay connected, find out what's going on around them and continue to access all the exciting content which is available at the touch of a button."
> Free WiFi to be offered on London Overground station via Sky's The Cloud
> Virgin Media bringing WiFi internet to London Underground stations