Nurmagomedov is the undisputed lightweight champion, while Poirier is the interim titleholder. UFC 242 is scheduled for Sept. 7 in Abu Dhabi.
Nurmagomedov's manager, Ali Abdelaziz, told ESPN Tuesday that his client signed a new multi-fight deal with the UFC before the Poirier bout was announced.
Terms of the deal were not disclosed, however Abdelaziz did say there are specific terms written into the contract in the event Nurmagomedov ever faces former two-weight champion Georges St-Pierre. St-Pierre is retired, but Nurmagomedov and Abdelaziz have continued to express interest in the fight.
Nurmagomedov (27-0) is one of the best pound-for-pound fighters in the world. "The Eagle" has never lost in the UFC, nor truly been threatened inside the Octagon. Nurmagomedov, 30, has not fought since beating Conor McGregor at UFC 229 last October. The Dagestan, Russia, native was suspended after that bout by the Nevada State Athletic Commission (NSAC) for nine months for his role in a post-fight melee with McGregor and his team.
Poirier (25-5, 1 NC) is on a six-fight unbeaten streak. The Louisiana native won the interim title by beating Max Holloway at UFC 236 in April. Poirier, 30, sports a 9-1 record (one no contest) since moving back up to lightweight in 2015 following a loss to McGregor.
"We have a tall order in front of us, Dustin Poirier is a great fighter and our main focus," Abdelaziz said. "None of these other guys have a guaranteed title shot, except for Georges St-Pierre. There is a clause in the contract for that fight. If Georges comes back, we're fighting Georges and it's already been negotiated.
"This deal is so massive for Khabib, Dana White had to go back to his pawn store and sell some of the stuff back he bought there. That's how big this deal is. We're extremely happy. It's a fair deal. And one of the things Khabib is most happy about is his father will be able to corner him in Abu Dhabi."
UFC 242 will be the promotion's first card in Abu Dhabi since 2014.
Abdelaziz also told ESPN that the UFC has signed Nurmagomedov's cousin, Abubakar Nurmagomedov, to an exclusive deal.
Nurmagomedov's teammate, Zubaira Tukhugov, will also remain under contract with the UFC. The Nevada State Athletic Commission recently shortened the lengths of suspensions on Abubakar and Tukhugov for their respective roles in the UFC 229 post-fight brawl involving McGregor. Abdelaziz said both fighters are good candidates to appear at UFC 242.
ESPN's Brett Okamoto contributed to this report.