The boyband's final ever show in Dublin's Croke Park on June 23 will be streamed live to 200 venues across the UK, Ireland, Europe, South Africa and Australia.
BBC Worldwide and content producer By Experience have inked a deal with Sony Music and Westlife to co-produce the live event.
Westlife said in a statement: "Over the past 14 years we were lucky enough to have a pop career that any band or musical artist would have been proud of. During that time we developed and built up an amazing bond with our fans all around the world.
"On June 23rd 2012 we will wrap our musical career as a band with one amazing final show in Croke Park Dublin, Ireland. We're working hard to make it everything we had ever dreamed of from our final concert - a farewell and a homecoming in front of 85,000 fans."
The group added that the gig will be "a hugely emotional night and we expect to have tears in our eyes for nearly every song.
"Westlife has changed our lives and this final night will live on in us all forever."
Salim Mukaddam, Director of Music at BBC Worldwide, said: "Westlife has been a major presence on the pop music landscape for the past 14 years.
"Only 85,000 fans can be present in the stadium, but we're delighted to be able to extend the event to their millions of fans across the UK, Ireland and further afield who can now be part of this incredible event at their local cinema."
The live broadcasts have been organised after the Croke Park concert sold out within five minutes.
Tickets for the cinema screenings are on sale now and can be purchased through the band's official website.
Watch the trailer for Westlife's last ever concert below: