This study explores the effects of a toxic workplace environment (TWE) on employee engagement (EE). Building on conservation of resources (COR) theory and organizational support theory (OST), this study proposed a research model. In this research model, a toxic workplace environment negatively affected employee engagement, directly and indirectly, through organizational support (OS) and employee well-being (EW). In this study, we used a quantitative research approach, and data were collected from 301 workers employed in the small and medium-size enterprises of China. To estimate the proposed relationships of the research model, we used partial least squares structural equation modeling (PLS-SEM 3.2.2). The results of this study confirmed that a toxic workplace environment has a negative impact on employee engagement. Moreover, the findings of this research confirm that organizational support and employee well-being significantly mediate a toxic workplace environment and employee engagement. The conclusions of this study are as follows: First, the direct relationship between a toxic workplace environment and employee engagement confirms that if employees are working in a toxic environment, they will spread negative feelings among other co-workers. The feelings that come with a toxic workplace environment, i.e., harassment, bullying, and ostracism, can be detrimental and lead to unnecessary stress, burnout, depression, and anxiety among the workers. Second, employee well-being will affect employee behaviors that enhance employee engagement with the work as well as with the organization. Third, organizational support also increases employee engagement with the work as well as with the organization. So, it is also confirmed that when workers perceive the support from the organization, their sense of belonging to the organization is strengthened.