This study investigated prevalence of premarital cohabitation among teenagers as perceived by undergraduates in Kwara State. Descriptive survey design was adopted for the study. Multi-stage sampling technique was adopted to select 210 undergraduates. Findings revealed that the major prevalence of premarital cohabitation among teenagers as perceived by undergraduates are: premarital cohabitation is common among teenagers who do not live with their parents; teenagers who have financial problem. The findings also showed that there were significant differences in the prevalence of premarital cohabitation among teenagers as perceived by undergraduates based on age and level of study. Also, the findings revealed that there were no significant differences in the prevalence of premarital cohabitation among teenagers as perceived by undergraduates based on gender and family type. It was recommended that there should be appropriate programmes well organized and coping strategies taught to young adults in order to minimize the prevalence of premarital cohabitation.