In Poland, there is little research on university students’ risky sexual behaviours. Additionally, existing studies analyse the behaviours selectively and do not group them into clusters. Hence, effective prevention is impossible. The research aims to gather information regarding the prevalence, forms and clusters of students’ risky sexual experiences. In 2019, a cross-sectional study was conducted in 12 universities in south-eastern Poland on a random sample (n = 2764). Fifteen risky sexual experiences, both condom-protected and unprotected, were analysed; they were mainly unprotected vaginal, oral, anal contacts; protected and unprotected sexual experiences while intoxicated and with unknown persons. Thanks Ward’s hierarchical method, four inseparable clusters of students with similar risky experiences were distinguished. Their dominant features were: (A) (24% of interviewees)—drunk partners, (B) (4.8%)—partners intoxicated with drugs, (C) (3.1%)—partner abuse and exceeding partner sexual norms, (D) (17.8%)—the anonymity of partners and going beyond the convention. It was stated that 60.3% of the respondents do not belong to any of the identified clusters. Sex education and the promotion of student sexual health should be intensified; the development of attitudes of avoiding risky sexual behaviours and dealing with their consequences should be considered.