Foxes and cats are the most abundant medium-sized urban carnivores. To date, however, there has been a lack of effort to synthesize data on the spatial and trophic resources used by these two carnivores, despite the importance of this information for assessing their similarity and roles in urban food webs. In this paper, we first synthesize all available information on the trophic patterns and home-range size of these two predators based on a total of 91 studies. Second, we conduct statistical analyses to test the influence of environmental and biological variables such as regional differences, habitat characteristics, age, and sexual status on their home-range size and diet patterns within urban habitats, and then evaluate the methods used to investigate these components. Our findings highlight the lack of studies that simultaneously monitor the diet and home-range size of both predators within urban habitats. To the best of our knowledge, this is the first study to compare fox and cat home-range size and diet. Foxes exhibited larger ranges than cats, while intact cats showed larger home ranges than desexed cats. Diet diversity obtained for both predators confirmed their trophic plasticity within urban habitats. Both predators consumed fewer mammals and invertebrates in highly disturbed habitats compared to medium ones. We also found that the procedure of data acquisition significantly influenced fox and cat home-range sizes. In terms of diet, the type of recovered samples had a significant effect on the diet composition of both predators. To improve our understanding of the relative impact of these two urban carnivores on urban wildlife, we recommend simultaneously studying both species in future studies. Moreover, methodological standards for both diet and home-range size studies are needed to allow comparisons.