This study examined the impact of unwanted pregnancy on the emotional and social wellbeing among senior secondary school students in Ibadan, Oyo state, Nigeria. Descriptive research design was employed and the cluster sampling technique was used to select 247 school-going adolescents. Both the independent and dependent variables were measured with relevant standardized instruments: emotional wellbeing, social wellbeing and unwanted pregnancy scales. Three research questions were raised and answered. The data obtained were analyzed using Pearson’s Product Moment Correlation Coefficient (PPMC) and Simple Percentage (frequency count). The findings revealed that unwanted pregnancy correlated with emotional wellbeing of the adolescent. Also unwanted pregnancy was related with social wellbeing. Further, it was revealed that the major cause of unwanted pregnancy was absence of sex education, followed by rape, lack of parental love and care, poor parenting style and divorced parents, Based on the findings of this study, it was concluded that unwanted pregnancy had significant impact on the emotional and social wellbeing of the in-school adolescents. It was therefore recommended that more attention should be given to sex education, as it is the bedrock of tackling the root cause of adolescents’ unwanted pregnancy.