Sky and NOW TV customers are set to lose access to Discovery's 12 UK channels next month, should the companies fail to reach a new agreement.
Earlier this month, Discovery threatened to pull its UK channels should negotiations fail.
According to Reuters, Sky has decided not to renew its contract on the terms offered by Discovery.
The blackout of Discovery channels will affect Sky+ HD, Sky Q, Sky Go and NOW TV viewers.
Discovery operates a number of television channels in the UK, including TLC, Animal Planet, and two Eurosport channels.
Discovery claims its channels attract more than 5.5 million people each week.
Following the "completely unrealistic" prices demanded by Discovery, Sky could lose the channels Sky Q: Everything you need to know about Sky's revolutionary TV service Fri, January 29, 2016
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However, Sky believes the price expectations set out by Discovery during negotiations were "completely unrealistic".
"We have been overpaying Discovery for years and are not going to anymore," a spokesperson for the company stated.
Meanwhile, Discovery has launched a campaign page on its website to encourage viewers to #keepdiscovery.
"Sky and NOW TV subscribers in the UK and Ireland could soon lose all of Discovery’s channels and programmes," the campaign webpage reads.
"Every week, more than five and a half million people watch one of our shows on Sky.
"Our fans are amongst the most loyal in TV and we have invested significantly to bring world class channels and high quality programmes to the UK for nearly 30 years."
Discovery has launched a campaign hashtag for the boardroom negotiations
Negotiations between broadcasters are nothing unusual, for example, Sky is always signing new contracts with content providers including HBO, ShowTime, and more.
However, it is rare that these boardroom disputes become quite so public – and it's almost unheard of that these behind-the-scenes negotiations have their own social media hashtags, like #keepdiscovery.
Sky Chief Executive Jeremy Darroch addressed the failing negotiations during Sky's quarterly earnings call this week.
He said: "Discovery viewing in the linear world has just been down significantly now for an extended period of time."
Adding that "their main channel Discovery is down by one-third over the last 10 years."
Sky will reportedly follow TalkTalk TV's decision to drop Discovery
Sky isn't the only provider that has recently reconsidered the value of Discovery's channels – TalkTalk TV quietly dropped Discovery last year.
When asked about the negotiations with Discovery, a spokesperson for Sky told Express.co.uk: "Despite our best efforts to reach a sensible agreement, we, like many other platforms and broadcasters across Europe, have found the price expectations for the Discovery portfolio to be completely unrealistic.
"Discovery’s portfolio of channels includes many which are linear-only where viewing is falling.
"Sky has a strong track record of understanding the value of the content we acquire on behalf of our customers, and as a result we’ve taken the decision not to renew this contract on the terms offered.
"We have been overpaying Discovery for years and are not going to anymore. We will now move to redeploy the same amount of money into content we know our customers value.
"Sky will continue to offer a huge range of content, from award winning documentaries to thrilling entertainment, with thousands of hours available to watch whenever and wherever our customers choose.
"Sky Sports customers can look forward to another huge year of sport, including the British & Irish Lions tour of New Zealand, unrivalled coverage of the Premier League, every F1 Grand Prix weekend, England’s home Test matches and the biggest competitions in golf, while all Sky TV customers can enjoy a selection of great sporting action at no extra cost, through the recently launched Sky Sports Mix channel."
The news comes as Sky announced a number of changes for new and existing subscribers.
For the first time, Sky is allowing users to watch without a dish.
The broadcaster is also introducing a new loyalty scheme that will reward and recognise members based on how long they’ve been with Sky.