<p>Understanding activity time budgets is crucial for analyzing primate behavioral variability and adaptation to environmental changes. Given the close interaction between wildlife and humans, conservation and management efforts must consider these phenomena. This study investigated the diurnal activity budget and diet of the olive baboon (<i>Papio anubis</i>) in and around the Chato Natural Forest in Oromia region, Ethiopia. We focused on two troops, namely the Bareda troop (inhabiting marginal areas of the forest where human interference is high) and the Dukko troop (occupying the central area of the forest, with little human disturbance). We used scan sampling to collect data on diurnal activity patterns and dietary regime. Bareda troop spent most of their time feeding, followed by resting, and then moving. Dukko troop also spent most of their time feeding, although less than the Bareda troop, followed by resting and moving. Fruits were the primary food source, comprising 53.4–72.7% of Dukko troop's diet and 33–54.4% of Bareda troops. Leaves constituted the second most significant dietary component, being consumed 8.7–16.3% and 20.9–39.6% of the time by the two troops respectively. Human encroachment alters baboon behavior and activity patterns, increasing competition for resources and heightening conflicts with humans. To promote better human-wildlife coexistence, efforts should focus on minimizing, human interference in natural primate habitats, allowing the animals to thrive and reducing conflict with human.</p>