BACKGROUND: Undernutrition is a frequent and serious problem in the world's older adults. Even though life expectancy is increasing, they are more vulnerable and at risk for nutritional problems. However, not much is known about the nutritional status of this group of the population, and they are often neglected. OBJECTIVE: This study was aimed at assessing undernutrition and associated factors among older adults in Womberma District, West Gojjam Zone, Amhara Region, Ethiopia, 2020. METHODS: A community-based cross-sectional study design was used among randomly selected 594 older adults aged above 60 years with a multistage simple random sampling method and proportional sample size allocation was used to address study subjects at the village level. The collected data was entered into Epi-Data version 4.2 and analyzed by using SPSS version 25. All variables with a p-value<0.25 in the bivariable analysis were considered for multivariable logistic regression for further analysis and the level of statistical significance was declared at p-value<0. 05. RESULTS: The prevalence of undernutrition among older adults was found to be 14.6% (95%CI: 11.9-17.7). A number of independent variables have a significant association with undernutrition, including gender, females [(AOR (95%CI): 3.14 (1.50-6.54)], age (Oldest Old [AOR (95%CI): 4.91 (2.44-6.08)] and Middle Old, [AOR (95%CI): 2.96 (1.44-6.08)], meal frequency [AOR (95%CI): 2.01 (1.12 (1.04-3.63)], dietary diversity score [AOR (95%CI): 2.92 (1.54-5.53)], depression [AOR (95%CI): 5.22 (3-9.07)], individuals with a sickness in the last 4 weeks [AOR (95%CI): 2.12 (1.02-4.41)] and individuals with a known hemorrhoid [AOR (95%CI): 3.51 (1.12-10.97)]. CONCLUSION: This study found that the prevalence of undernutrition in older adults is high and needs attention. Sex, age, meal frequency, dietary diversity, being sick in the last 4 weeks, having hemorrhoids, and depression were the associated risk factors. Therefore, the government, family members, and other stakeholders should give more attention to older individuals.