Objective To evaluate the level of information possessed by pregnant adolescents regarding the human papillomavirus (HPV). Methods Descriptive study developed in the adolescent prenatal outpatient clinic of a tertiary hospital from the state of São Paulo, Brazil. Data were collected between June and December 2017 following approval from the ethics and research committee (CAAE: 1.887.892/2017). Pregnant adolescents, ≤18 years old, who attended the abovementioned outpatient section, composed the sample. Those diagnosed with a psychiatric disorder and those with hearing or cognitive disabilities were excluded. After acceptance to participate in the present study, the pregnant adolescents signed an Informed Consent Form. Regarding the statistical analysis, the chi-squared test and the Fisher exact test were used. Results Regarding the knowledge about HPV, 123 (80.92%) of the participants had already heard about the subject; for 77 (50.66%), their schools had been the source of the information; 101 (66.45%) did not know how they could be infected by the virus. Age variation did not influence their knowledge on how to prevent themselves from HPV (p = 0.2562). The variable vaccine is associated with HPV prevention (p < 0.0001). Conclusion The pregnant adolescents composing the sample have shown to have knowledge about HPV. However, they do not prevent themselves from it appropriately, given that little more than half of the sample was vaccinated, had not reported an understanding that the use of preservatives and vaccination are effective means of prevention, and did not correlate HPV with uterine cervical cancer.