We understand that child labour causes serious mental and physical health issues among children in Pakistan. We borrowed positivist epistemology as a guide for the methodological application of this study to understand what are the determinants of child labour? and how do they affect children’s physical and mental health? Using the laminated sampling technique, data for this study come from 100 children. After the management of data through SPSS (statistical package for social sciences), the quantitative content analysis technique helped us in data analysis. The study concludes that poverty, parents' unemployment, and children's school dropout are the major causes of child labour in Pakistan. Moreover, this study finds that child labour causes stress, frustration, aggression, and depression among the children. This study recommends that parents, government, and non-governmental organizations need to jointly devise long term policies to cope with the issue of child labour in Pakistan.