Background Young person’s susceptibility to sexually transmitted infection has been consistently linked to intractable work places. In Ethiopia, different behavior related interventions had carried out to raise awareness of risky sexual behaviors and their consequences. However, there is still limited information on risky sexual practices. Methods A cross-sectional study was conducted among the big construction site daily laborers from April 1, 2019 to May 30, 2019. A pre-tested questionnaire was used for data collection, and data were entered into Epidata and transported to SPSS for analysis. Independent variables with p < 0.05 in the multivariate analysis were considered to have a statistically significant association with risky sexual practice. Result Among 627 sample respondents, the magnitude of risky sexual practice was found to be 24.2%. Labor workers who had a history of an STIs (AOR = 4.29; 95% CI: 2.56, 7.19), those who enjoy in the nightclubs (AOR = 2.33; 95% CI: 1.34, 4.08), those who started sex by peer pressure (AOR = 3.42; 95% CI: 2.06, 5.68), substance users (AOR = 2.03; 95% CI: 1.08, 3.82), those who were unable to read and write (AOR = 3.65; 95% CI: 1.41, 9.67), living independently (AOR = 3.71; 95% CI: 1.78, 7.77) and living with relatives (AOR = 3.12; 95% CI: 1.06, 9.20) were statistically associated with risky sexual practice. Conclusion The magnitude of risky sexual practice among big constriction daily laborers was high in Bahir Dar City likely to increase their vulnerability to HIV. The findings of this study show the need of targeted HIV prevention plan to give due attention for daily laborers who had a history of an STI, enjoy in the night clubs, peer pressure, substance users, educational status and living arrangement. The Amhara Education Bureau and the city education department have to design ways to deliver at least a high school education.