‘Solid waste management has been identified as a massive problem in especially developing countries, and there is no specific solution found for that. It is also a topic that gradually comes with a growing population, rapid urbanization, and fast development. There are two parties involved in waste management activities in the developing world, the formal sector and the informal sector. Both sectors play a specific role in the solid waste management process, but there is no official contact between these two sectors, which has an impact on the weekly waste management process. The purpose of this study is to investigate the formal and informal sectors' contributions to the waste management system, the importance of informal sector involvement in solid waste management, and to identify opportunities for integrating both sectors into the waste management process. Here, mass balance analysis is used to identify the waste flow within the boundary, and an integrated visualisation tool is used to identify possibilities for integrating formal and informal sectors in this Municipal solid waste management process. The result suggests the potential for integrating these two sectors in the municipal solid waste management system. It will provide mutual benefits for both sectors, public, health, and environment. Based on the findings, integration of both sectors will be a better solution for the solid waste management system in Sri Lankan cities.