Coronation Street, EastEnders and Emmerdale are among a number of soaps joining together for the very first crossover episode.
The storyline will be focused on climate change and will begin airing from November 1.
Soap queen Sharon Marshall appeared on This Morning to announce the news and hailed it as "amazing".
She told hosts Holly Willoughby and Phillip Schofield: "It's the first time it's ever been done. In November, we're going to be having the world's first soap crossover. Now for the first time, all five British soaps - and our continuing dramas - they're all going to come together and tell the same story at the same time. That story is going to be climate change."
Among those involved include Casualty, Coronation Street, Doctors, EastEnders, Emmerdale, Holby City and Hollyoaks.
She continued: "All of these people have been talking about it in secret for months and months to make this work and what they're each going to do is film a scene, have a reference that is going to cover a different aspect of climate change and - this is the fun bit - a soap first.
"You're going to see all the programmes do a nod to the other and characters will start popping up from one soap in another soap on screen. That has never been done before."
A social media video featuring two of Emmerdale's residents will also be shown to Corrie characters, while one of Doctors stars will be shown to Corrie characters.
Meanwhile, Casualty will be discussed in The Woolpack and a social media clip from Weatherfield will be talked about in The Queen Vic.
Emmerdale's Executive Producer Jane Hudson came up with the idea and has been in contact with other soap producers.
She said: "Never before have all five soaps and both continuing dramas come together and united in telling one story. And we certainly haven't seen characters pop up in other shows before. This is a real treat for our audience, whilst also allowing us to get across a very important message.”
While BBC Studios' Head of Continuing Drama Kate Oates said: "I’m thrilled that our soaps and serial dramas have all come together to help highlight the issue of climate change amongst our millions of viewers. We’re grateful to the teams that made this happen, and hugely look forward to seeing the talent from our own shows popping up in other iconic programmes.”
Hollyoaks boss Lucy Allan added: "We know how important climate change and environmental issues are to our youthful audience, and to all soap viewers. It has been great to work together on an engaging way to, hopefully, inspire conversations about issues that are so important."
*The big week will begin airing November 1
