UFC president Dana White made the announcement during a news conference Friday. The lightweight title bout will headline UFC 229 inside T-Mobile Arena.
McGregor (21-3) has not fought in the UFC since November 2016. He made his professional boxing debut in an unprecedented big-money fight against Floyd Mayweather Jr. last August. McGregor lost via TKO in the 10th round.
The Dublin native will attempt to reclaim the 155-pound championship he was forced to relinquish in April due to inactivity. Nurmagomedov (26-0) won the title and became the UFC's undisputed champion at UFC 223 in April, defeating Al Iaquinta by unanimous decision.
"I wouldn't say this is a crossroads fight," White said about McGregor, when asked about what's at stake for McGregor's legacy. "This is a very important fight for both fighters. For Khabib, who is undefeated and who is looked at as one of the best fighters in the world, beating Conor is massive for him.
"And obviously for Conor, coming back from a two-year layoff, in my opinion -- and it's crazy to say this because of how popular he is around the world -- but he's one of the most underrated fighters in the UFC. Everybody thinks because he speaks so well and gets so crazy and everything, it makes him sort of less of a fighter. It's the weirdest thing I've ever seen."
McGregor, 30, accepted a plea deal from the Brooklyn District Attorney's office last week for his involvement in an incident inside Barclays Center, two days prior to UFC 223. McGregor threw a metal dolly into a bus that was transporting UFC fighters, two of whom suffered injuries.
McGregor pleaded guilty to a single disorderly conduct violation, avoiding jail time and a criminal record. He was sentenced to five days of community service, anger management and full restitution to the bus company.
White said he wasn't worried about any disruptive behavior from either McGregor or Nurmagomedov for the upcoming fight.
White on what's at stake for McGregor
Dana White talks to Brett Okamoto about Conor McGregor's return to the UFC and what it means for McGregor's legacy.
White said there would be no world tour for the fight, but that the UFC "will do some fun stuff for the media, the fans. This is an easy fight to promote. But we'll put in the work."
Nurmagomedov, of Dagestan, was the alleged target of the attack. He had confronted McGregor's close friend and teammate Artem Lobov in a hotel lobby during UFC 223 fight week, and that apparently prompted McGregor's actions.
Despite his lengthy absence from the UFC, McGregor is still considered one of the top lightweights in the sport. In 2016, he became the first fighter in UFC history to hold two titles simultaneously, at featherweight and lightweight. The UFC ultimately stripped McGregor of both due to inactivity.
"When you talk about pound-for-pound, best in the world? This is a guy who is actually living proof for pound-for-pound. He [McGregor] jumps from weight class to weight class and fights people in different weight classes," White said. "He went out and boxed Floyd Mayweather, and he is literally willing to fight anybody in the world who thinks they're better than him. It's what makes him so popular. This isn't a crossroads fight. This is another fight to cement his legacy as one of the best to ever do it."
Nurmagomedov has replaced McGregor as the most dominant force in the division and is the No. 3 pound-for-pound fighter in the world, according to ESPN. Stylistically, he is a dominant wrestler, compared to McGregor's reputation as a devastating striker.
The Westgate Las Vegas SuperBook opened McGregor as a +150 underdog in his return fight against Nurmagomedov (-180).