The deal follows reports last month that the launch of a 24-hour US BBC News channel could be getting closer as the corporation extended its BBC World News service to offer hours of early morning news.
BBC World has secured a three-hour block on BBC America, replacing half-hour bulletins. It marked the first time BBC World News has broadcast for three hours straight in the US.
The BBC's international news and entertainment channel will initially only be available to RealNetworks' subscribers. A 14-day free trial is being offered at and builds on the availability of selected BBC World News programming, which is already broadcast in around 86m US homes daily on PBS, and at breakfast time on BBC America.
The BBC said that recent independent research has shown a 40% increase in the US audience demand for international news.
Sian Kevill, BBC World's editorial director, said: "BBC World News can deliver this, and has a worldwide reputation for impartial and accurate reporting, and this is at the core of what our teams do to ensure we bring the stories behind the headlines to our audience."
The deal is an extension of a longstanding deal between the BBC and RealNetworks in Europe.
Dan Sheeran, senior vice-president of music and video at RealNetworks, said: "We are thrilled with the opportunity to offer our US SuperPass members the highly regarded coverage of BBC World News. Our members will now have access to live coverage of world events and programming 24/7."
Jeff Hazell, BBC World's director of distribution and business development, said: "We have received great interest from a number of US operators looking to take the BBC World News channel on a full-time basis.
"Our partnership with RealNetworks in the US is a first for BBC World News and we believe that it will generate further audience demand for the channel and bring us closer to launching a 24-hour offer on US cable, satellite and other digital platforms."
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