ObjectiveThis study aimed to investigate the prevalence of low back pain and its associated factors among high school teachers in the West Arsi zone, Southwest Ethiopia.DesignA school-based cross-sectional study was conducted from February to March 2020. A self-administered structured Nordic Musculoskeletal questionnaire was used to assess low back pain during the past 12 months. Bivariate and multivariable binary logistic regression analysis was carried out using Stata V.14. The degree of significance was obtained at a 95% CI and p<0.05.SettingThe study was conducted in the West Arsi zone, Ethiopia.ParticipantsA total of 602 teachers participated in this study.Outcome measuresThe primary outcome is the prevalence of low back pain.ResultsThe prevalence of low back pain during the last 12 months was found to be 63.73% (95% CI 59.77% to 67.70%). About 225 (39.61%) teachers experienced moderate pain, and (89.79%) of them had a minimal disability. Being unmarried (adjusted OR (AOR) 0.47, 95% CI 0.28 to 0.79), prolonged standing (AOR 2.31, 95% CI 1.16 to 4.60), sleeping disturbance (AOR 3.22, 95% CI 1.41 to 7.36), regular physical activity (AOR 0.52, 95% CI 0.33 to 0.84), current smoker (AOR 2.83, 95% CI 1.04 to 7.67), lifting heavy load (AOR 1.96, 95% CI 1.17 to 3.28), psychological job demand (AOR 2.86, 95% CI 1.69 to 4.84) and job satisfaction (AOR 0.46, 95% CI 0.27 to 0.79) were associated with low back pain.ConclusionThe prevalence of low back pain was high in this study. Prolonged standing, sleep disruption, heavy load lifting, cigarette smoking and psychological job demand were risk factors for low back pain. Physical exercise and workplace satisfaction were effective interventions. Emphasis should now be put on ergonomics, regular physical activity and psychosocial factors to lessen the problem.