Also available are Discovery, MTV, Comedy Central, GOLD, Disney and FOX.
The channels are available on the NOW TV Box and via NOW TV app on PS3 and Roku. Mac and PC users can also stream the channels on their computers.
Sky says it will also make them available via iPhone, iPad, selected Android smartphones, Xbox, LG Smart TVs and selected LG media devices “over the coming months”.
The channels are offered on a rolling monthly basis, meaning viewers don’t have to commit to lengthy fixed term plans.
Sky already offers its movie and sport channels via NOW TV which it launched to combat the growing threat from low-cost streaming services such as Netflix and Amazon’s Lovefilm.
In addition to live shows such as The Blacklist, Dracula and Game of Thrones, the new TV package includes access to entire box sets of hit shows including The Wire and Mad Dogs.
Gidon Katz, Director of NOW TV, comments: “Millions of people can now go online to watch some of the best entertainment channels, including Sky 1, Sky Atlantic and Comedy Central. NOW TV offers pay-as-you-go access to brand new episodes of home-grown British shows and the biggest and best US series for anyone with broadband.”