Rodent pests are a serious problem for agricultural production in globally. In Ethiopia, however limited researches have been carried out on rodents and in particular there is no scientific document on the population ecology of rodent pests around Koga Irrigation Farm. Therefore, this study was conducted to make ecological assessment on diversity, relative abundance, and habitat association of rodents from March to September 2021. Stratified random sampling technique was applied to classify habitats. A total of 6 sample site from three representative habitats (Eucalyptus plantation, maize farm, and wheat farm) were selected. A 7x7 locally made live trapping grid with 10 m spacing, and 5x5 snap traps with 20 m spacing were employed for three consecutive days per each grid. A Shannon-Weaver diversity index was used to estimate rodent species diversity. Overall 259 individuals of rodents belonging to three species were captured in the area. Of which, 173 were captured by live traps in 1764 trap nights and 86 by snap traps in 900 trap nights with a trap success of 9.8% and 9.6%, respectively. The highest relative abundance was recorded for Arvicanthis abyssinicus (45.03%) followed by Rattus rattus (31.13%) and Stenocephalemys albipes (23.84%). More individuals of rodents were captured during the wet season than the dry season. The diversity of species varied among habitats as well as between the wet and dry seasons. There was significant variation in the relative abundance of rodents among habitat types (2 = 14.02, df = 2, P = 0.001). However, all habitats have similar species richness. The highest diversity (H’=1.05) was recorded in wheat farm, while the lowest (H’=1) was in maize farm. More number of juveniles and pregnant females were recorded during the wet season showing that breeding in rodents reaches its peak during the wet season. Koga Irrigation Farm harbors high numbers of rodent pest species. Thus, it needs proper monitoring and management strategies.