"The Notorious" was granted a boxing license from the California State Athletic Commission a year ago but was unable to attain a license in Nevada due to his bottle-throwing fiasco with Nate Diaz at the UFC 202 pre-fight presser.
White said his plan now was to try to lure the American out retirement for a super fight with McGregor.
Chances are, however, that after McGregor faces Mayweather, all this talk with subside.
"It is an honor to sign this record-breaking deal", McGregor said in a statement to the mixed martial arts site The Mac Life.
No date or location has been discussed yet for this potential fight, but White said earlier this month that the two sides were targeting September 16, which has since been taken by the boxing match of the year in Canelo Alvarez vs. Gennady Golovkin. Later he declared the Mayweather fight the only match he was interested in pursuing, and claimed he had the legal authority to go ahead if the UFC tried to stop him.
The 28-year-old told TheMacLife: "The first, and most important, part of this historic contract has now officially been signed off on". Congratulations to all parties involved.
"This is a Liam Walsh and Gervonta Davis press conference, let's focus on these two competitors", Mayweather said.
Mayweather has the speed, talent, defensive skills, and experience to beat McGregor, which is the main prediction of what will happen when and if these two fight. "That's total disrespect to both of these fighters".
Mayweather earned between $220 million and $230 million when he fought against Philippine boxer Manny Pacquiao in 2015, ESPN reported.
Here's what Floyd's had to say about the bout previously: "I came out of retirement because I'm a businessman and I want to give the world what they want to see". 2016 Rio Olympics - Boxing - Quarterfinal - Women's Middle (75kg) Quarterfinals Bout 245 - Riocentro - Pavilion 6 - Rio de Janeiro, Brazil - 17/08/2016.