Bothrops mattogrossensis occurs in open wet habitats in the Pantanal of western Brazil. As part of a series of studies focusing on how ecological characters evolved in the genus Bothrops, we gathered information on diet, reproduction, and morphology for B. mattogrossensis using museum specimens. Bothrops mattogrossensis has a generalized diet (anurans, small mammals, lizards, snakes, and centipedes), a plesiomorphic character in the genus Bothrops. We found no evidence of an ontogenetic shift in diet from ectothermic to endothermic prey, as observed in other species of Bothrops. Feeding frequency is high (68.8%) compared to other Bothrops spp. Reproduction is seasonal, with a vitellogenic period concentrated at the end of the dry season. Fecundity is relatively high, with clutch size varying from 18–37. Females are significantly larger in snout–vent length and have significantly shorter tails and relatively larger heads than males. Although mostly terrestrial, B. mattogrossensis is relatively slender and has a longer tail than other terrestrial Bothrops, possibly an adaptation for climbing into vegetation during seasonal floods.