This study investigated the prevalence and consequences of substance abuse among undergraduates in Kwara State. The study examines whether or not moderating variables such as age, gender and family type would influence the respondents’ view on the prevalence and consequences of substance abuse among Undergraduates in Kwara State. The descriptive survey research design was adopted for the study. A simple random sampling technique was used to select 60 respondents from each of the three selected institutions. Thus, a total of 180 respondents participated in the study. A researcher-developed questionnaire titled "Prevalence and Consequences of Substance Abuse Questionnaire (PCSAQ)" was used to collect data for the study, using a t-test and Analysis of Variance (ANOVA) at 0.05 level of significance. The findings of the study revealed that the prevalent substances among undergraduates in Kwara State are cigarettes, alcohol, and tobacco among others. The findings also revealed that the consequences of substance abuse among undergraduates in Kwara State are low self-esteem, dropping out of school, and social isolation (i.e. Poor relationships with others) among others. The findings of this study also revealed that there was no significant difference in the prevalence and consequences of substance abuse among undergraduates based on age and family type. However, a significant difference was found in the prevalence and consequences of substance abuse based on gender. Based on the findings, it was recommended 1) that undergraduate students should be properly oriented by the counsellors on the dangers associated with substance abuse at the beginning of their academic year, 2) seminars and workshops should be provided by counsellors so that students would be informed about the consequences of substance abuse, 3) education should be properly structured and provided to students by school counsellor and parents at the early stage of development and 4) counsellors should organize seminars on the prevalence and consequences of substance abuse on the health of individual.