The promotion initially wanted Oleinik, who is from Moscow, to face former champion Fabricio Werdum. That fight was scrapped in May, however, when Werdum was notified by the United States Anti-Doping Agency (USADA) of a potential violation. That case is still pending.
The UFC Fight Night event will take place at Moscow's Olympic Stadium.
Oleinik (56-11-1) is coming off a submission win over Junior Albini in May. That is the 41-year-old's only appearance of 2018 thus far. He is 5-2 overall in the UFC.
Hunt (13-12-1), originally of New Zealand, will be looking for his first win of the year. He is 1-2 in his past three contests, with losses to Curtis Blaydes and Alistair Overeem. His most recent win is a TKO victory over Derrick Lewis in June 2017.