Nurmagomedov, who lost his father to coronavirus related complications earlier this month, will try to defend his title against Gaethje.
Khabib Nurmagomedov will fight Justin Gaethje on October 24, UFC president Dana White told CNN on Tuesday.
White did not reveal the fight's location but told CNN he is confident the fight, originally scheduled for September, will proceed.
"It's going to happen, tell you right here right now. That fight is going to happen," White said.
Nurmagomedov's father and trainer, Abdulmanap, died on July 3 in a Moscow hospital from coronavirus-related complications. In an emotional Instagram post last week, Nurmagomedov posted a photo hugging his late father and said, "You will be missed Father, you were Father, friend, brother and coach all rolled into one. You taught me almost everything that I can, I hope you were pleased with me. After all, the contentment of parents is the contentment of Allah."
White told CNN Sport's Don Riddell that the death has been hard on the 31-year old.
"His father was a hero to him, he loved his father, they had a very close relationship and it was very hard on him," White said.
In May, Nurmagomedov took to Instagram to talk about the impact COVID-19 has had on his life.
"In my personal case, I've had more than 20 people sick from my family," he said in comments translated by ESPN. "More than 20 people were lying in the ICUs. And many of them are no longer among us. Many acquaintances have died, many parents of my relatives. Everybody is having a hard time dealing with it."
The announcement comes two months after Gaethje stepped in for Nurmagomedov in UFC 249 and defeated Tony Ferguson for the interim UFC lightweight title.
Nurmagomedov, the reigning champion, was originally slated for the bout but was unable to travel due to coronavirus restrictions.
Following the win, Gaethje took off the belt and said, "I'll wait for the real one."