Background: Malnutrition is a major public health concern among older adults in low- and middle-income countries, contributing to increased morbidity, functional decline, and mortality. In Ethiopia, the population aged 60 years and older is projected to rise steadily, yet data on their nutritional status remain scarce. This study aimed to assess the nutritional status and associated factors among adults aged 65 years and older in Harar town, Eastern Ethiopia. Methods: A community-based cross-sectional study was conducted from April 30 to May 29, 2023, among 413 randomly selected adults aged ≥ 65 years in Harar town. Nutritional status was assessed using the validated Mini Nutritional Assessment–Short Form (MNA-SF). Data were entered into EpiData v3.1 and analyzed in SPSS v25. Bivariate and multivariable logistic regression identified factors associated with malnutrition. Crude and adjusted odds ratios (AOR) with 95% confidence intervals (CI) were reported, with statistical significance set at p < 0.05. Results: The prevalence of malnutrition was 15.2% (95% CI: 0.18–1.91), and 43.6% (95% CI: 0.38–0.48) were at risk of malnutrition. Factors significantly associated with malnutrition included older age groups from 75 to 84 years (AOR = 4.45; 95% CI: 1.25–15.77) and 85 to 95 years (AOR = 6.54; 95% CI: 1.36–31.31), low educational attainment (AOR = 6.15; 95% CI: 1.26–29.9), recent illness (AOR = 3.16; 95% CI: 1.07–9.26), presence of chronic illness (AOR = 6.48; 95% CI: 2.22–18.86), and poor dietary diversity (AOR = 6.25; 95% CI: 1.38–28.10). Household food insecurity, mild (AOR = 5.62; 95% CI: 1.35–23.30), moderate (AOR = 6.67; 95% CI: 1.69–26.38), and severe (AOR = 6.92; 95% CI: 1.05–45.22), was consistently associated with increased odds of malnutrition.Conclusion: Malnutrition and its risk are common among older adults in Harar town. Key factors include advanced age, chronic illness, poor dietary diversity, and household food insecurity. Public health interventions should focus on improving dietary intake, strengthening nutrition education for older adults and caregivers, and addressing household food insecurity.