The three-year agreement was announced ahead of the 2015 final between Arsenal and Aston Villa at Wembley.
The deal, which is reportedly worth at least ??30m, will begin next season and will see the Dubai-based company become the competition???s lead partner until 2018.
The FA has been seeking a new sponsor for the tournament since Budweiser???s three-year association with the competition ended 12 months ago.
Next season???s competiton starts on August 15 with the extra-preliminary rounds and the final will take place on Saturday, May 21, 2016.
Emirates has been involved in a number of sporting sponsorships around the world over the last decade or so.
They are currently tied into one of the biggest such contracts in football with Arsenal, holding their shirt sponsorship rights until 2019 and stadium naming rights until 2028.
FA chairman Greg Dyke said: “Emirates’ commitment to our sport is evident and securing such an iconic and forward-thinking lead partner for the FA Cup is great news for us, the fans and for the whole game.
“The partnership will help take the tournament to new audiences, inspire interest in football from across the globe and allow us to continue our investment into the game at all levels.”
Sir Tim Clark, president of Emirates, added: “Football is a truly global sport, a unifying factor in many communities and nations across the world.
???Never is this more evident than with the FA Cup, which has an unrivalled heritage and draws a global audience of more than 1.1billion people.
“The spirit of the competition, fair play and sparking the passions of a global audience are all values we share at Emirates.
???That is why we are proud to be the first title sponsor of the tournament and we look forward to a long-term partnership to support and connect fans to their teams both here in the UK and across the world.”