Although developing a green supply chain is a topic of growing interest in the hotel industry, research on hospitality green supply chain management (GSCM) is limited. This study investigates the effect of internal and external measures of GSCM on environmental cost reduction, and how environmental cost reduction improves the supply chain performance with the mediating role of agility and resilience of a green supply chain. Data were collected from 370 employees of the top-rated hotels in Tehran, Iran, and analyzed using structural equation modelling in SmartPLS software. The findings revealed that internal and external measures of green supply chain management have a positive and significant effect on the environmental cost reduction of hotels. The reduction in environmental costs directly affected the variables of green supply chain agility, green supply chain resilience and green supply chain performance. The findings also confirmed the mediating role of green supply chain agility and resilience between environmental cost reduction and green supply chain performance. Overall, the study reinforces that addressing environmental measures in the hotel industry could have favourable consequences for hotels to improve supply chain performance.