3:19 PM PT -- Floyd just posted a picture of the signed contract on his Shots page ... saying, "What the world has been waiting for has arrived."

He added, "Mayweather vs. Pacuiao on May 2, 2015, is a done deal. I promised the fans we would get this done and we did."

Floyd Mayweather Jr. is making it official what we already knew was coming for weeks -- TMZ Sports has learned his fight with Manny Pacquiao is set, the deal is signed -- and they'll be getting it on in Vegas on May 2nd.

As we previously reported, the two fighters reached an agreement to get in the ring back in January -- and the major issues, including date and location have been set for weeks.

The fight is expected to be the richest contest in boxing history -- with both pugilists projected to take in well over 100 million dollars.

Good work if you can get it folks ...