Holm defeated Ronda Rousey in December but has lost her title in her first defence.
Fiery featherweight champion steps up two divisions against UFC stalwart at the MGM Grand Garden Arena.
Holm puts her women's bantamweight belt on the line for the first time since knocking out Ronda Rousey.
McGregor was due to face Rafael dos Anjos in title bout before the lightweight champion injured his foot.
Holm will make her first defence of bantamweight belt she won by knocking out Ronda Rousey.
While Mayweather is now retired, McGregor holds his next fight against Nate Diaz at UFC 196 this weekend.
High production values are to be expected of EA Sports
Experienced middleweights did not disappoint during epic five-round battle at London's O2 Arena.
Middleweight bout takes place at the O2 Arena, on a card that also features Tom Breese and Arnold Allen.
Diaz steps in for the injured Dos Anjos, while McGregor will move up two weight classes.
Reports suggest that the UFC are now searching for a replacement after Brazilian broke his foot in training.
Rousey lost both her title and her unbeaten record following shock second-round defeat in Melbourne.
Mixed martial arts legend Kevin Randleman died on Thursday due to heart failure.
Dana White had hoped to schedule the bout for UFC 199 in June, but it will now be pushed back.
Cage fighter convinced his in-laws to help him run at least three farms in houses in Hertfordshire
"The Notorious" is looking to become the first fighter in UFC history to hold two world titles concurrently.
In only his second bout since 2011, the injury-plagued Cruz won via split decision at TD Garden in Boston.
All you need to know ahead of the title clash between bantamweight rivals at TD Garden in Boston.
Dillashaw provides the third defence of his belt against former champion at UFC Fight Night 81 in Boston.
Lawler is favourite in the bout in Las Vegas, Nevada. Find out how to follow the fight in the UK.
IBTimes UK look back on who stood out in sport in 2015.
The Dubliner must make a decision over which weight division to occupy.