Long-lasting insecticide nets are often used as a physical barrier to prevent infection of malaria. In sub-Saharan Africa, one of the most important ways of lowering the malaria burden is the utilization of long-lasting insecticide-treated nets. However, there is no sufficient information on long-lasting insecticide utilization in Ethiopia. Therefore, the study was aimed to assess long-lasting insecticide net utilization and associated factors among households of West Arsi Zone, Oromia, Southern Ethiopia, 2023. A community-based cross-sectional study design was conducted in West Arsi Zone with a sample of 2808 households from May 01 to 30, 2023. Data were collected from households by using interviewer-administered structured questionnaires. Data were checked, coded, and entered into Epinfo version 7, cleaned, and analyzed by SPSS version 25. Descriptive analysis was used to present frequencies, proportions, and graphs. Binary logistic regression analysis was computed and the variables with p-values less than 0.25 were selected to be included in the multivariable model. The final model was interpreted using an adjusted odd ratio with a 95% confidence interval and p-value < 0.05 to declare the statistical association between the outcome and independent variables. About 2389 (86.2%) of households have long-lasting insecticide nets that can be used while sleeping. But the overall prevalence of long-lasting insecticide nets utilization was 69.9% with (95% CI 68.1–71.8). Being female as household head (AOR 1.69, 95% CI 1.33–4.15), number of separate rooms in the living house (AOR 1.80, 95% CI 1.23–2.29), duration of long-lasting insecticide nets used to be replaced (AOR 2.81, 95% CI 2.18–5.35), knowledge status of the respondents (AOR 3.68; 95% CI 2.48–6.97) were significantly associated with long-lasting insecticide nets utilization. The overall Household’s level of LLINs utilization was found to be low as compared to the national standard of Ethiopia, which is to be ≥ 85. The study identified that being female as household head, the number of separate rooms in the living house, the duration of long-lasting insecticide nets used to be replaced, knowledge status of the respondents were the predictors of long-lasting insecticide nets utilization among members of households. Thus, to improve the usage of LLINs, the West Arsi Zone Health Office and stakeholders should strengthen the long-term insecticide net utilization at the household level by educating the community with appropriate information.