Sources confirmed the planned matchup to ESPN on Monday. The televised event will take place at CenturyLink Arena.
Dos Santos (18-5) hasn't fought since he challenged Stipe Miocic for the heavyweight title last May. The 34-year-old lost the bout via TKO.
Originally from Brazil and now fighting out of South Florida, dos Santos was sidelined in 2017 by a failed drug test in August. The United States Anti-Doping Agency (USADA) eventually suspended him for six months, while also announcing the failed test was caused by a legal tainted supplement.
For Ivanov (16-1), the main event will mark his UFC debut. The Bulgarian heavyweight is a decorated wrestler and figures to be an interesting addition to the division. He has fought in WSOF and Bellator MMA previously.