The sponsorship kicks off in the 2013/14 season, marking the Irish cider brand’s first foray into the world of football.
Tom McCusker, managing director of Magners, said: “Magners is a premium brand with huge ambition both at home and abroad, available in over 40 markets worldwide including key cider growth territories like the US, Australia, Canada and Asia.
"There is, therefore, a great fit with Celtic Football Club who also enjoy great success and popularity domestically and internationally.
“Everyone at Magners is looking forward to working with Celtic and its fans over the coming years in what promises to be an exciting time for the club and our brand.”
The club is currently sponsored by Tennent’s, which, like Magners, is owned by Dublin-based C&C Group.
The sponsorship began in 2010 and is reported to be worth around £1.5 million per year.
The new sponsorship represents an increase in funding, but the club would not divulge the full details.
Celtic chief executive Peter Lawwell said: "This partnership is magnificent news, not only for Celtic but also for Scottish football. We are proud to be successfully leading Scottish football at home and in Europe.
"The desire of a brand with Magners’ stature to support the club is a measure of how much positivity there is around Celtic in our 125th year. I look forward to a long and successful partnership with Magners and I’m sure every Celtic fan will welcome their support.”
The deal with Magners means it will be the first time since 1999 that Celtic and great rivals Rangers have not shared the same jersey sponsor.