Ensuring the sustainability of hospital waste management practices has become a burning issue. Due to the growing population coinciding with rapid urbanization and industrialization, practicing sustainable methods of medical waste management is an urgent requirement. Like other developing countries, Sri Lanka also faces various difficulties when dealing with high-risk hospital waste material, spreading diseases rapidly and making the environment unclean. Thus, moving towards sustainable hospital waste management has received urgent attention. The primary purpose of this study is to explore whether the existing hospital waste management practices are sustainable. Further, this study identifies weaknesses of the existing waste management practices and examines factors affecting Sustainable Hospital Waste Management (SHWM) in the Western province of Sri Lanka. Data were collected from 18 officers involved in waste management from 14 government hospitals in the western province. Both inductive and deductive thematic analyses were used to explore whether the hospital waste management practices are sustainable. The study revealed that most selected hospitals failed to achieve sustainability in waste management practices. Achieving sustainability of waste management practices has become a challenge to government hospitals due to financial constraints, limited facilities and infrastructure, lack of social support, and poor management and administration. Patient mindset and health capacity, positive attitudes, knowledge, awareness, and experience, training on hospital waste management, availability of basic infrastructure and resources, financial facilities for hospital waste management, availability of rules and regulations, and intra and inter-organizational supports significantly affect sustainable hospital waste management. Exploring the sustainability of waste management practices using empirical data related to Sri Lanka is an initial attempt in the sustainable hospital waste management literature. Finally, policy measures are suggested for sustainable hospital waste management in Sri Lanka.