Microsoft originally said the app would launch between now and next spring, but a Sky representative has now clarified it will launch in the summer, according to Videogamer.
"We enjoy a long track-record of innovating with Microsoft and look forward to the launch of NOW TV on Xbox One by summer next year," reads the statement.
"As a dedicated over-the-top service, we have prioritised the availability of NOW TV, to extend the reach of the service to the main TV.
"Looking ahead, we will also consider any future opportunities for Sky Go."
Xbox One entertainment apps expected to launch by spring include 4OD, LOVEFiLM, Netflix, Twitch and Machinima.
All apps have been built from the ground up for Xbox One, offering voice and gesture controls, as well as the opportunity to introduce exclusive Snap features and media achievements.
Other system features confirmed for launch include Xbox Fitness, Xbox Video, Xbox Music, Internet Explorer, Skype, SkyDrive, and Video Upload.
The BBC recently said that it was working with Microsoft to bring the iPlayer app to the Xbox One in the future.
Xbox One will be available on November 22 in North America and parts of Europe.
Microsoft recently released two new TV commercials ahead of launch