Many developing countries are now facing rapid urbanization with cities struggling to provide essential services such as housing, clean water, reliable power supply, sanitation facilities, and transportation services. Urban growth has also resulted in loss of green spaces, pollution, social inequalities, and increased vulnerability to disasters and climate change. Application of science, technology and innovation (STI) can help developing countries address these issues and achieve sustainable urban development. Developing countries are well-placed to leverage STI through leapfrogging by adopting new environment-friendly technologies and innovations, rather than following the traditional path of development. However, because of economic and technological hurdles, developing countries are not always in a position to adopt new technologies, which implies that it is equally crucial for developing countries to leverage existing technologies that are cost-effective, scalable, easy to operate and maintain, environmentally friendly, and economically beneficial. In this chapter, we explore how developing countries can apply STI to address complex urban issues central to sustainable urban development such as improving urban planning and design, managing urban infrastructure and services (e.g., water supply, wastewater treatment, municipal waste management, and transportation), promoting local food production, and building urban resilience against disaster risks and climate change. We also discuss challenges and way forward for developing countries regarding application of STI for sustainable urban development. By adopting and adapting appropriate technologies, these countries can address complex urban issues, improve service delivery, promote environmental sustainability, and enhance the quality of life for their urban populations. However, concerted efforts and collaborative partnerships are needed to overcome the challenges and ensure the effective application of STI for sustainable urban development in developing countries.