Launched earlier in the year, NOW TV offers streaming of Sky Movies content either via subscription or pay-per-view. It will expand to entertainment and sports content "in the next few months".
Users of Roku LT and Roku 2 XS boxes can from today access NOW TV within the Roku Channel Store, enabling them to browse and stream a range of new and classic movies over a home WiFi network.
As with other compatible platforms, such as iPad and YouView boxes, Sky is offering Roku customers a 30-day free trial of NOW TV, but also a three-month introductory subscription offer of £8.99 a month.
Alongside a range of movies, Roku users who get NOW TV will soon be able to enjoy a range of live broadcasts from Sky Sports, including Premier League and UEFA Champions League football and England Test cricket.
Earlier in the year, Sky made an undisclosed investment in Roku, the company that makes low-cost streaming media players which compete with the likes of Google TV and Apple TV.
Roku products offer around 300 channels of entertainment, such as on-demand films and TV; live sports from MLB.TV and Ultimate Fighting Championship; music from Rdio; photos and videos from Facebook and Flickr; news from The Wall Street Journal; and casual games such as Angry Birds.
NOW TV director Simon Creasey said that "more and more" consumers are getting their entertainment over internet-connected devices.
"Following today's launch on Roku, our customers now have another way of streaming their favourite movies to their main TV screen, while continuing to enjoy access out and about via iPad and smartphones," Creasey said.
"At the same time as we're rolling NOW TV out to new platforms and devices, we're also preparing to increase the range and choice of great Sky content that our customers can access."
> Sky's NOW TV move 'risky', analyst warns
> Sky agrees new movie rights deal with Universal
Roku vice president and general manager of Europe Clive Hudson added: "NOW TV is a tremendous addition to the growing selection of entertainment available from Roku.
"NOW TV is a really compelling content proposition for UK consumers who want to enjoy watching the latest movies from Sky, and with no long-term contract."