UFC president Dana White announced the 155-pound matchup during a news conference on Tuesday. The UFC 205 pay-per-view will take place at Madison Square Garden.
Nurmagomedov (23-0) had campaigned for a title fight against defending champion Eddie Alvarez (28-4). White attempted to book that fight, but Alvarez held out for a title defense against current featherweight champion Conor McGregor.
The UFC ultimately granted Alvarez's request and booked the fight between him and McGregor. That bout is scheduled to headline UFC 205.
Nurmagomedov, of Dagestan, quickly switched gears and signed up for a fight against Johnson. According to sources, the UFC offered to pay Nurmagomedov a purse to stay ready in the event of an injury to the main event, but Nurmagomedov asked for an opponent and a fight instead.
The 28-year-old fights out of American Kickboxing Academy and is 7-0 in the UFC, although he has been limited to just one appearance in the past two years due to injury.
Johnson (17-10) is coming off a stunning first-round knockout of Dustin Poirier earlier this month. Fighting out of Blackzilians in Boca Raton, Florida, Johnson is 9-6 in the UFC.