In the past two decades, fast growing population and energy demand has prompted the Government of Pakistan (GoP) to maintain investment in imported fossil fuels. For a developing country under a large circular debt, this has inhibit Pakistan to bridge the energy demand-supply gap. Recent social mobilisations and awareness on the degradation of national environment has forced GoP to consider and promote the deployment of new and renewable energy technologies for power generation. In 2019, the Alternative and Renewable Energy policy represented a turning point in national energy planning. Energy modelling has become an increasingly important tool for country intending to meet their NDC targets. By utilising OSeMOSYS, this study explores most cost-effective pathway towards energy transition and security in the short-, medium-, and long-term. Three scenario are drawn from this study: Least Cost (LC), Fossil Future (FF), and Net-Zero (NZ). Results provides key insights on installed capacity and production, as well as emissions, costs and investment for each modelled scenario. Thus, under a comprehensive overview of Pakistan energy system, variable renewable energies (VRE) are seen to have the highest potential to support energy transition while feeding national demand. It is later discuss ways to implement VRE to further sustainable energy transition in Pakistan. This include the impact of such technologies in energy security, most cost-effective options, and co-benefits, without excluding existing challenges. Recommendations for planning a renewable future in Pakistan focus on further assessment of energy demand and economic growth, improving efficiency, generating investment, and coal- phaseout. Whilst this study was successful under determined framework, some limitations invite further research to be conducted.