Mycophagy (fungi consumption) is an important animal-ecosystem interaction, and provides important nutrients for numerous mammalian taxa, such as primates. Although mushroom consumption is a widespread behaviour in about a quarter of all known primate species, surprisingly little is known about their use of mushrooms as either a staple or fallback food, and the relationship between mushroom availability and consumption. We used four years (2019-2023) of direct observational data on mushroom consumption in the diet of three sympatric primate species (Chimpanzees, Pan troglodytes schweinfurthii; Yellow baboon, Papio cynocephalus; Red-tailed monkey, Cercopithecus ascanius) in a mosaic woodland habitat in the Issa valley, western Tanzania to address these gaps. We analysed mushroom consumption patterns and assessed mushroom availability from line transects for a period of 15 months (Oct 2022 – Dec 2023). Our findings show that mushrooms were an important dietary component for all three species when availability was high in the early-mid wet season (chimpanzees – 3 %, baboons – 22 %, and red-tailed monkeys – 3 %), while baboons also continued to consume mushrooms (>10 % of their diet) even when availability was low later in the year. We conclude that mushrooms serve as a fallback resource for Issa chimpanzees and red-tailed monkeys, while they represent a preferred food for Issa baboons. We contextualise mushroom consumption as a potential strategy of niche partitioning to reduce inter-specific feeding competition as well as underscore the importance of mycophagy and its role in primate dietary ecology and human evolution.