Despite fashion consumers' desire to protect the environment and behave in a socially responsible manner, the reality of the environment within the fashion retail industry is far from sustainable, as evidenced by several infamous scandals that continue to afflict fashion businesses. Though corporate sustainability is gaining traction with both consumers and businesses, the USA and China may exist in different institutional contexts in regard to corporate sustainability. Consequently, this study was designed to understand the differences in employees' perceptions toward corporate sustainability, and how employees in fashion retail businesses engage in organizational citizenship behaviour in the USA and China. By using a sample of 615 fashion retail employees from the USA and China, this study conducted Multivariate Analysis of Variance and multiple linear regression analyses to determine the differences between these two countries and their demographic characteristics. The study found that employees in China revealed a greater preference for transparency in production and operation than did US employees. The importance of corporate sustainability yielded quite opposite results according to age and gender differences. Overall, this study found that both US and Chinese employees perceived sustainability to be highly important for corporations to achieve, but only US employees were engaged in organizational citizenship behaviour with the influence of their MRCS. Hence, this study's findings provide better insight for global fashion retail businesses in that they may have to exercise different strategies to achieve corporate sustainability in different countries, as the employees might have different levels of moral expectations based on their country of employment.