UFC on Fox: Poirier vs. Gaethje (also known as UFC on FOX 29) was a mixed martial arts event produced by the Ultimate Fighting Championship that was held on April 14, 2018, at the Gila River Arena in Glendale, Arizona.

Zuffa had previously hosted the final World Extreme Cagefighting event, WEC 53 at the arena in December 2010.

However, the pairing never materialized as Vannata was unable to accept the fight for this date as he was still rehabilitating a recent arm injury.

However, Alhassan was removed from the event, citing injury and was replaced by promotional newcomer Ricky Rainey.

However, on April 2, Brown pulled out of the fight due to a torn anterior cruciate ligament and was replaced by Alex Oliveira.