Said the pair in a statement: "Comcast and Netflix have reached an agreement to incorporate Netflix into X1, providing seamless access to the great content offered by both companies. We have much work to do before the service will be available to consumers later this year. We'll provide more details at that time."
Sources said deal to be on the cable giant's set-top box would be akin to the arrangement that Netflix has cut with smaller cable operators in the United States and bigger ones across the globe. Netflix also has deals with Apple, Roku and Google's Chromecast, in which its app is offered on these Internet TV services. It also is embedded in smart televisions.
A recent report by Morgan Stanley, in fact, raised this possibility of a Comcast deal, especially noting that Comcast could benefit by getting a larger bounty from Netflix for adding subscribers. It would also help Comcast have a more competitive video offering to others like Roku, Dish that have apps from services like Hulu and Netflix.
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For Netflix, the addition of new subscribers would be a big benefit and it would also put them closer to a wider range of consumers.
The move is an enormous step, given the long and sometimes contentious history between the two companies against a backdrop of increased consumer usage of Internet-delivered video.
Back in 2012, for example, Peter Kafka reported that Netflix CEO Reed Hastings was "once again accusing Comcast of violating 'Net neutrality' principles by favoring its own Web video service over those from Netflix, HBO and Hulu, when it comes to data usage."
In 2014, the pair struck a deal aimed at clearing the bottleneck of slowing the video service's streams for the cable company's broadband customers, though Hastings later expressed regret at having to forge it and Comcast also groused back.
Without going into all the details, let's just say Comcast and Netflix have had some issues.
The deal also lets the cable giant show regulators that they are more open and that their X1 box is a Web video platform and not just an old-time cable box with a better user interface.
More to come, obvi.
—By Kara Swisher, Recode.net.
Disclosure: Comcast is the owner of NBCUniversal, the parent company of CNBC and CNBC.com. NBCUniversal is an investor in Recode's parent Vox, and the companies have a content-sharing arrangement.