This study has utilized household level survey data of Multiple Indicator Cluster Survey (MICS) wave 6 to estimate inequality of opportunities of child well-being in Pakistan. To achieve this objective, Human Opportunity Index has been constructed by using children's reading skills, numeracy skills, schooling, and nutrition as a set of outcome variables related to child well-being. Shapley's decomposition method has been used to estimate the contributions of different circumstances in determining inequality of opportunities across these outcomes. Our findings suggest that mother's education, father's education, household's economic status, region of residence (provinces), area of residence (rural/urban) and gender of child are important factors for inequality of opportunities of child well-being. Region of residence (province) remains the most important factor in explaining inequality of opportunities of reading skills, numeracy skills and schooling as it contributes 40.35% to inequality of numeracy skills, 30.37% to inequality of reading skills, and 26.43% to inequality of schooling whereas household's economic status is the most important factor to explain the disparities in children's nutritional outcomes with a contribution of 26.94%. These findings provide valuable insights into the issue of inequality of opportunities and can help policymakers to formulate policies to bridge the identified gaps and promote a fair and inclusive society in Pakistan.