Abstract Understanding primate ecology requires studying population dynamics and estimating their density. Baseline information on the number of animals that can be observed has been provided by studies of primate populations. However, olive baboons (Papio anubis) are not routinely counted in the Chato Natural Forest. The aim of this study was to determine the population size of olive baboon in a natural Chato forest. The population structure of the identified olive baboon groups was established via the total count method. Data were collected from January 2022 to October 2022. The chi-square test was used to compare the number of olive baboons counted between the wet and dry seasons. To compute the variation among different age groups and sex ratios, an olive Baboon student’s paired t test was used. Tables and graphs were used to present the results. To distinguish between each unique group of olive baboons during both the wet and dry seasons, eleven different sleeping cliffs were discovered in the Chato Natural Forest. These eleven counting locations differed significantly from one another in counting the population. The results revealed that throughout the dry and wet seasons, 787 and 857 olive baboons, respectively, were counted. The population density of Anubis baboons during the wet and dry seasons was 32.9 and 30.2 Anubis baboons per km2, respectively. For the development of conservation measures, estimating the population density of olive baboons in and around the Chato Natural Forest was crucial