Per ESPN's Ariel Helwani, Bellator officials confirmed the deal and noted that it is for multiple fights.
Usman is a perfect 11-0 professionally with seven wins by way of knockout and three by submission. Helwani noted that Usman is considered a "major prospect" in the sport.
Usman is following in the footsteps of his cousin, who is among the most successful fighters in the history of the UFC.
The 32-year-old Khabib is the reigning UFC lightweight champion and owns a perfect professional record of 28-0 with 10 submissions and eight knockouts. Among the fighters he has beaten are Conor McGregor, Dustin Poirier and Rafael dos Anjos.
The COVID-19 pandemic has prevented Khabib from competing since UFC 242 in September 2019, but he is lined up for a fight against interim UFC lightweight champ Justin Gaethje in October.
There are some clear similarities between Khabib and Usman, but one major difference is that Khabib has a decorated background in judo and sambo, while Usman specializes in Muay Thai.
According to Helwani, Bellator officials said the current plan is for Usman to compete in the lightweight division and make his debut for the promotion in December or January.