Objective Social phobia is highly prevalent among university students. The lowest and highest point prevalence of social phobia among undergraduate university students was estimated at 7.8% and 80%, respectively. However, research into social phobia and associated factors among undergraduate university students in low and middle-income countries has been limited. Therefore, this study aimed to assess social phobia and associated factors among university students in Ethiopia to contribute an attempt to ensure optimal care for students. Result A total of 503 participants were interviewed with a response rate of 100%. The mean age of the respondents was 22.17 (± 10) years. The prevalence of social phobia symptoms among students was found to be 31.2% with (95% CI 27.3 to 35.6%). In the multivariable analysis, poor social support (AOR = 2.8, 95% CI 1.40, 5.60), female sex (AOR = 2.3; 95% CI 1.50, 3.60), 1st-year students (AOR = 5.5; 95% CI 1.80, 17.20), and coming from a rural residence (AOR = 1.6; 95% CI 1.00, 2.40) were factors significantly associated with social phobia symptoms. Electronic supplementary material The online version of this article (10.1186/s13104-019-4482-y) contains supplementary material, which is available to authorized users.