Among medium-sized carnivores, red foxes (Vulpes vulpes) and domestic cats (Felis silvestris catus) are the most abundant species in human-dominated landscapes worldwide. Both are known to be generalist predators that exploit a wide range of prey groups (e.g., mammals, birds, and invertebrates). Identifying red fox and domestic cat predation pressure on shared prey could shed light on their ecological role in shaping wildlife communities in human-dominated landscapes. Here, we assess the seasonal diet of red foxes and domestic cats in terms of composition, breadth, and overlap. Over two years, we collected their scats across three human-dominated study sites: park (n = 220 for foxes and n = 0 for cats), agricultural land (n = 159 for foxes and n = 146 for cats), and managed forest (n = 169 for foxes and n = 47 for cats). We detected similar diet breadth (B) for red foxes and domestic cats (B = 0.32 and B = 0.36, respectively) as well as strong dietary overlap (O = 0.83) between them. Moreover, the diet composition of both predators varied according to the study sites and seasons. Our results confirm the highly flexible trophic behaviour of these carnivores at the study sites, probably as a consequence of prey availability, and also the simultaneity of their predation over the same prey groups. Future studies should simultaneously monitor predator diet as well as predator and prey abundance in human-dominated landscapes to better understand the predatory impact of red foxes and domestic cats.