Sky Go Extra is being offered on top of the Sky Go service that allows the 10m+ Sky customers to watch live and on-demand TV on multiple devices, such as Android smartphones or an Apple iPad.
By paying a £5 monthly subscription fee, Sky Go Extra customers can download blockbuster films from Sky Movies and content from channels such as Sky1 and Sky Atlantic to watch on their device to watch without the need for a WiFi or 3G/4G connection.
Available to all Sky customers, Sky Go Extra also allows its subscribers to register up to four Sky Go devices, rather than two on the main offering.
Launched in 2011 when Sky Player and Sky Mobile TV merged into one service, Sky Go now offers live and on-demand programmes from 43 channels and attracts more than 3m unique users each quarter, according to Sky.
The pay-TV giant feels that the new Sky Go Extra package will give greater flexibility for people wanting to watch content on their device even when without an internet connection, such as on a train or flight.
The £5 monthly fee allows Extra customers to download movies and TV shows to a smartphone, tablet or laptop, where they will stay available for a 30 day period.
Sky Go Extra customers will be able to download shows from channels such as Sky Atlantic, Sky1 and Sky Arts, as well as partner networks including Disney and Nickelodeon.
Sky said that customers with a 64GB iPad would be able to store in excess of 400 half-hour TV shows and more than 80 movies.
Sky Go Extra is being billed as "the first mobile TV subscription service in the UK and Ireland to offer Hollywood movies to download and watch offline".
But downloads on Extra still depend on a customer's Sky TV subscription. Anyone who is not already a Sky Movies pack customer, will not be able to download films such as Avengers Assemble, Sherlock Holmes: Game of Shadows and classic James Bond films to their device.
Alongside the downloads option, Sky Go Extra customers can register up to four, rather than two, internet-connected devices, giving them more scope to stream and download content.
Sky Go Extra will appear within Sky Go and come as an update in all the respective app stores. To sign up to the service, customers should visit the Sky Shop, including the offer of a two-month free trial of the service until the end of March.
Also today, Sky has said that three more Android devices will be added to Sky Go - the HTC One X+, the Motorola RAZRi and the Samsung Galaxy Tab 2 7.0.
In addition, Sky has released some facts about Sky Go use in 2012, including that Bad Teacher, Transformers: Dark of the Moon and Captain America: The First Avenger were the three most popular movies on the service last year.
On the TV side, the second seasons of Karl Pilkington's unique travel show An Idiot Abroad pulled in 2.5m views in 2012, while the latest season of Game of Thrones generated 1.1m views on Sky Go.