A fifth of all species in the carnivorous‐insectivorous marsupial family Dasyuridae show obligate male semelparity (die‐off), where males die after their first mating season, but females may breed in more than one season. Life history strategies of many species in the genera Antechinus and Phascogale are well known, but the other dasyurid genus with apparently obligately semelparous males, Dasykaluta, is poorly known, and there have been no demographic studies of this monotypic genus in the wild. Both sexes in Antechinus and Phascogale species are highly polygamous. Comparative and experimental tests of insectivorous marsupials indicate that this polygamy is linked to the evolution of semelparity in more strongly seasonal breeders, through intense sperm competition. We assessed whether the kaluta (Dasykaluta rosamondae), a small dasyurid endemic to the broader Pilbara region of Western Australia, has obligate male semelparity, multiple paternity within litters, and positive testis allometry in the wild. We documented complete die‐off of males over two breeding seasons. Multiple paternity was confirmed in seven of eight litters, where either two or three fathers sired young. The seven young in the remaining litter appeared to be sired by one male. Intraspecific positive testis allometry was found in adult males. We conclude that the life history strategies of wild male and female kalutas are consistent with those of the two other genera of dasyurids with obligate male semelparity (Antechinus and Phascogale), and sperm competition is likely to be important in the mating system of kalutas. Our results show that male obligate semelparity has evolved twice in dasyurids.