The WHO-5 well-being measure happens to be one of the most renowned measures of subjective well-being across the globe. Although the instrument has been calibrated in different countries, its psychometric properties and applicability in Africa, especially in Ghana, are not known. In this study, the WHO-5 well-being scale was validated among adolescents in Ghana by assessing the validity evidence of the measure based on the internal and external structure. In particular, the study examined the (1) dimensionality of the WHO-5 well-being scale, (2) quality of the items (including the scale functioning) for the measure, and (3) criterion validity of the well-being measure. Using a survey approach, 997 adolescents were recruited in secondary schools across the northern belt of Ghana. The study found a one-factor structure of the scale, which supports the factor solution of the original measure. The items were found to be of high quality, except for one item. The WHO-5 well-being measure was found to have sufficient evidence regarding convergent and divergent validity. The outcome of this validation study provides support for the validity and reliability of the WHO-5 well-being scale’s utility and use among adolescents in Ghana. The study encourages further validation studies to be conducted in Ghana to widen the reproducibility of the WHO-5 well-being measure.