Sexually Transmitted Infections (STI) are a group of infectious diseases spread through unprotected sexual intercourses, resulting in curable and incurable diseases. The syndrome is a variety of clinical signs and symptoms caused by pathogens that can be acquired and transmitted through sexual activity. Around the world estimated about 376 million people become infected each year with one of four common curable STIs where about 86 million new cases of curable STIs occurred in the African region. The objective of this study to assess the magnitude and associated factors for Sexually transmitted infections in 2020 among Hawassa industrial park workers, Southern Ethiopia. The multistage sampling technique was used to select a total of 663 study participants. The data were entered into the Epi-Data version 4.4 and analyzed by SPSS version 21. Both bivariate and multivariable logistic regression analyses were employ P-values of <0.05 and AOR with 95%CI was used to determine the presence of association between covariates and dependent variable.. The Self-reported STI magnitude in the last 12 months was 18.7% (18.54-18.91) among the Hawassa industry park workers. Hometown residence [AOR=2.29; 95%CI: 1.34-3.92], drinking alcohol (AOR=3.26; 95%CI: 1.74-6.09), view/read pornography (AOR=4.38; 95%CI: 2.67-7.18) and poor knowledge (AOR=2.69; 95%CI: 1.65-4.420 were significantly associated with the magnitude of STIs. The Self-reported magnitude of STIs among Hawassa Industrial Park was found to be high.