Background/aim Approximately 50% of water polo players have suffered orofacial injuries. However, fewer than 8% of players wear a mouthguard. A more comfortable mouthguard design is therefore needed to increase compliance. The aim of this study was to assess the effect of reducing the palatal extension of a custom‐made mouthguard on the degree of satisfaction with a mouthguard among water polo players. Materials and Methods Eighteen elite water polo players participated in this randomized crossover trial. Two custom‐made mouthguards were fabricated for each participant using 4‐mm‐thick ethyl vinyl acetate foils, defined by the extension of the palatal margin from the cervical line: conventional (6 mm) and shortened (2 mm). The mouthguards were worn during all training sessions and matches, in a randomized sequence (one mouthguard type for the first and fourth weeks and the other for the second and third weeks). Mouthguards were evaluated on 10‐point scales for discomfort, interference with oral functions, protection, and general satisfaction after each training session or match. Results Players evaluated the shortened mouthguard as having less interference with speech (Effect 1.30; P < 0.001), breathing (Effect 0.98; P = 0.004), swallowing (Effect 1.30; P < 0.001), and athletic performance (Effect 0.61; P = 0.03) compared with the conventional mouthguard. The perceived degree of protection was similar among participants when wearing each type of mouthguard. Overall, players were more satisfied with the shortened mouthguard (Effect 0.64; P = 0.03). Conclusions Reducing the palatal extension of a custom‐made mouthguard from 6 to 2 mm improves the overall satisfaction of elite water polo players without affecting the perceived degree of protection.