UFC on ESPN 66 in Kansas City was filled with exciting fights and memorable moments. Zhang Mingyang spoiled Anthony Smith's retirement fight with a first-round TKO victory. Mingyang, now 3-0 in the UFC, overwhelmed Smith with heavy ground and pound, forcing the referee to stop the fight at 4:03 of Round 1. Smith, a former light heavyweight title challenger, retired after the loss, leaving his gloves in the center of the octagon after a career spanning over 20 fights in the UFC.

Malcolm Wellmaker made a stunning debut, knocking out Cameron Saaiman in the first round. Wellmaker, who earned a contract through Dana White's Contender Series, landed a clean counter right hook that led to the stoppage at 1:59 of Round 1. Following his victory, Wellmaker expressed his excitement and set his sights on competing at UFC Fight Night 257 in Atlanta.

Randy Brown delivered a violent knockout against Nicolas Dalby in the second round, becoming the first fighter to finish Dalby in his 30-fight career. Brown dominated the fight, utilizing his range and sharp punches. The finish came at 1:39 of Round 2 when Brown connected with a powerful right hand, sending Dalby crashing to the canvas. The fight was highly praised, with many noting Dalby's toughness despite the brutal finish.

Michel Pereira suffered a unanimous decision loss to Abus Magomedov, with Magomedov dominating the fight. Pereira's performance lacked his usual flash and flair, leading to criticism from other fighters, some suggesting that Pereira put more energy into his pre-fight dance than the actual fight itself. The loss marks Pereira's second straight defeat.

Other notable results from UFC on ESPN 66 include David Onama's unanimous decision victory over Giga Chikadze, Ikram Aliskerov's first-round TKO win against Andre Muniz, and Jaqueline Amorim's submission victory over Polyana Viana.