Guinness is already the sponsor of the Premiership domestic competition in England.
A new rugby campaign will feature England captain Lewis Moody, Lee Byrne of Wales and Scotland’s Sean Lamont.
They will appear in online video diaries and on in-store POS.
The three-year deals include signage, pouring rights, tickets and hospitality at each union’s home fixtures.
Marketing director John Roscoe said: “These new partnerships give us our largest-ever presence in rugby and demonstrate our long-term commitment to the sport.”