Aim: Biosafety is a set of preventive measures aimed at controlling risk factors arising from biological, physical, and/or chemical agents. This topic is particularly important in the dental field since saliva is the main biological agent of the transmission of coronavirus. The present study aimed to determine the factors associated with the level of knowledge about biosafety against COVID-19 in Peruvian dentistry students. Materials and Methods: The present observational, cross-sectional, and analytical study evaluated 312 Peruvian dentistry students. A validated 20-question questionnaire was used to measure the level of knowledge. The nonparametric Mann–Whitney U and Kruskal–Wallis tests were used to compare levels of knowledge between categories of each variable. A logit model was used to evaluate associated factors such as sex, age, marital status, place of origin, academic year of study, being in the academic upper third, history of COVID-19, and living with vulnerable family members. A significance level ofp< 0.05 was considered. Results: 36.2%, 31.4%, and 32.4% presented poor, fair, and good knowledge levels, respectively. Students under 25 years of age were 64% less likely to pass the biosafety against COVID-19 questionnaire than students 25 years of age and older (OR = 0.36; CI: 0.20–0.66). Students in the academic upper third were nine times more likely to pass the test than other students (OR = 9.38; CI: 4.61–19.07). Finally, third-year students were 52% less likely to pass the exam than fifth-year students (OR = 0.48; CI: 0.28–0.83). Conclusion: Only a minority of dentistry students had a good level of knowledge about biosafety against COVID-19. Younger and less educated students were more likely to fail the questionnaire. On the other hand, those students with outstanding academic performance were more likely to pass the questionnaire.