The deal, which is in place until the 2013/14 season, will see an expansion of live broadcasts of Magners League games into Ireland, Scotland and Northern Ireland.
Most regular season home matches involving Leinster, Munster and Connacht will be available free to air in Ireland on either RTE or TG4 with a scheduled kick-off mostly of Friday or Saturday evening.
BBC Northern Ireland will focus on Ulster home games, with Friday evening as the preferred kick-off time, whilst Edinburgh and Glasgow Warriors games will be covered by BBC ALBA.
BBC Wales and S4C continue with their established Friday and Saturday evening timeslots, with most of their games scheduled for those times.
All broadcasters will enjoy reciprocal feeds, so they can follow their local teams for vital away games, whilst all have agreed to provide live coverage of any end of season Play-Offs matches that fall within their territories.
In welcoming the agreement, David Jordan, Tournament Director, Magners League, said: "It is very good news that we now have strong broadcast partners in the UK and Ireland. Terrestrial free to air television increases access for fans of the Magners League to one of the most competitive tournaments with some of the best-known players in world rugby.
"Our new broadcasters, BBC ALBA, BBC Northern Ireland, RTE and TG4 compliment our existing partners, BBC Wales and S4C, and will provide unparalleled coverage of Magners League games in the coming season."
John Hussey, Chairman of Celtic Rugby and IRFU Junior Vice President commented, "This is a very welcome development for the Magners League as a growing competition.
"With such strong and established terrestrial sports broadcasters committing themselves to the League, it can only continue the development of the competition and is an example of the balance of free-to-air coverage that is needed to support the game in the competing unions."
Dominic McKay Scottish Rugby's, Director of Communications and Public Affairs, added: "We are delighted that both Edinburgh and Glasgow Warriors will receive significantly increased broadcast coverage for the seasons ahead.
"Securing regular live coverage of Glasgow Warriors and Edinburgh matches has been a focus for Scottish Rugby in recent seasons and we welcome today's announcement by BBC ALBA.
"Both Glasgow and Edinburgh enjoyed a successful season last year and it's great news for rugby and sports fans in Scotland that they will now have access to regular live coverage of both professional teams.
"We look forward to working closely with BBC ALBA in the seasons ahead."
HOW TO WATCH Magners League GAMES NEXT SEASON
BBC ALBA
Available UK-wide on Sky channel 168 and Freesat 110. It is available streamed and on seven-day catch-up on iPlayer
BBC ONE Northern Ireland
Virgin channel 863, Sky 973
BBC TWO Northern Ireland
Sky channel 992
Freeview BBC1 NI & BBC2 NI only available in Northern Ireland
BBC TWO Wales
In Wales on Freeview channel 2, digital satellite (Sky and Freesat) 102, and Virgin 102
Outside Wales via digital satellite on channel 991.
RTE
Only available in the island of Ireland
S4C
In Wales on Sky channel 104, Freeview 4, Virgin 167, Freesat 104
In England, Scotland and Northern Ireland on Sky 134 and Freesat 120
TG4
Only available in the island of Ireland
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland