This chapter reports an online survey study investigating how startup CEOs’ use of motivating language influences their employees’ advocacy behavior. Informed by interdisciplinary theories, the study proposes that employee relational outcomes and their identification with startups as serial mediators explain the impact of startup CEOs’ use of motivating language on employee advocacy behavior. Through an online survey of 1,027 startup employees across various industries in Mainland China, the study found that startup CEOs’ use of motivating language positively influences employees’ advocacy behavior toward their company directly and indirectly through enhanced employee-startup identification and employee-startup relationship outcomes. This study advances the theoretical implications and explanatory boundaries of motivating language theory in the context of leadership and entrepreneur communication in the unique startup context in China. It also provides practical insights for startup leaders and entrepreneurs regarding effectively engaging startup employees.