UFC on Fox: Weidman vs. Gastelum (also known as UFC on Fox 25) was a mixed martial arts event produced by the Ultimate Fighting Championship held on July 22, 2017, at the Nassau Veterans Memorial Coliseum in Uniondale, New York.

[6] A light heavyweight bout between Gian Villante and Patrick Cummins was originally booked for UFC Fight Night: Lewis vs. Abdurakhimov in December 2016.

[8] A heavyweight bout between Christian Colombo and Damian Grabowski was expected to take place at UFC Fight Night: Gustafsson vs. Teixeira.

[10] Subsequently, Colombo was removed from the fight on June 22 for undisclosed reasons and was replaced by Chase Sherman.

[11] Alessio Di Chirico was expected to face Rafael Natal, but pulled out in the weeks leading up to the event due to a neck injury and was replaced by promotional newcomer Eryk Anders.