The fight was held according to the rules of boxing and ended in the first round.
Belfort knocked out Holyfield.
In the main battle, two former UFC fighters met - Anderson Silva and Tito Ortiz.
The fight ended with a victory for Silva, also by knockout.
Former US President Donald Trump, commenting on the fight, congratulated Belfort on his victory.
Earlier, Belfort announced his intention to knock out de la Hoya.