In a new stage of booming platform economy, improving the employees’ job security is the key factor to ensure the sustainable development of a platform organization. Based on the cognitive behavior theory, this study introduces the perceived insider status as the moderator variable, and constructs the process mechanism model of job insecurity on employee engagement. The aim of this study is to examine the relationship between job insecurity, emotional response and employee engagement, and provide suggestions for reducing job insecurity and improving employee engagement. Using a 2-wave time-lagged survey data of 341 workers in China firms, data were collected with a self-report questionnaire and analyzed with the statistical package for the social science (AMOS, SPSS). The research result found a negative relationship between job insecurity and employee engagement, and that this negative relationship was mediated by negative emotion or positive emotion. Furthermore, perceived insider status moderated the relationship between job insecurity and positive emotion or negative emotion; the higher the perceived insider status is, the weaker the negative impact of job insecurity on positive emotion and the weaker the positive impact on negative emotion. The research results provide theoretical guidance for organizations to improve employee engagement and help to strengthen the importance of organizations to employees’ job insecurity.