Sky and BT have have signed a deal to sell their channels on each other’s platforms.
Under the deal, BT will now supply its sports channels – which show UEFA Champions League and Premier League football – to Sky.
In addition, BT will be able to sell Sky’s Now TV service – which includes Sky Sports, Sky Cinema and the Sky Atlantic channel – to its customers.
The new services will be available to customers from early 2019.
BT has spent more than £3.5bn on Champions League and Premier League football rights since 2012 in an attempt to compete with Sky.
Gavin Patterson, chief executive of BT, said: “This is an important day for BT and for our customers, who will be able to enjoy a whole range of Sky’s sport and entertainment programming on their BT TV boxes.
“This is the next logical step for our TV and content strategy. We feel that now is the right time to broaden the ways in which we distribute BT Sport.
Sky boss Jeremy Darroch said: “This is great news for Sky customers who will be able to access all matches on Sky and BT channels from the Premier League, UEFA Champions League and Europa League directly with a single Sky TV subscription and with the great customer service that we provide.”
Richard Broughton, research director at media analysts Ampere, said the deal was “certainly very unusual”.
“It is a consequence of increasing [costs of] sports rights,” he said.
“The new rights are up for renewal very soon and this is a pre-emptive shot from both companies to limit their exposure to damage should they not get key rights and also allow them to be a little less aggressive in their bidding.”
He added that online giants such as Facebook and Amazon were the “unknown factor” in terms of what they might bid for in sports rights auctions.
Huge online firms have been part of a seismic shift in how people access content.
On Thursday, Disney announced a deal to buy a large chunk of 21st Century Fox, including its 39% stake in Sky.
Media mogul Rupert Murdoch told Sky News on Thursday he was selling Fox’s entertainment assets in part due to the rise of online giants.
“[Amazon and Netflix] are growth companies… Amazon, I don’t know how much they want to do. They are spending $5bn or $6bn I believe on new programmes, but it’s basically to widen the appeal of [Amazon] Prime.
“Anyone who joins Prime seems to spend about $3,000 immediately on retail… you know, they are a huge disruptor if you look at what they’re doing.”
“Amazon – every businessmen wants to attack it or defend against it, but the public loves it,” he added.
He said the new Fox company that remained would have the strength to bid for sports rights, but that all companies could be “threatened by big nonsensical bids from the likes of Facebook”.