<p>Teachers’ work engagement plays an important role in terms of students receiving a healthy education and the sustainability of educational processes. However, most of the studies on work engagement have been conducted using cross-sectional designs. The fact that the long-term effects of teachers’ work engagement, which is a fundamental element of education, have not been examined creates a significant gap in the literature. This study aimed to examine the longitudinal relationship between organizational ostracism, future anxiety, and work engagement in teachers. The longitudinal mediating role of future anxiety in the relationship between organizational ostracism and work engagement was examined with a two-wave cross-lagged panel model in a Turkish sample (<i>N</i> = 387). The results revealed that future anxiety played a partial longitudinal mediating role in the relationship between organizational ostracism and work engagement. The findings proved that teachers who experienced organizational ostracism felt anxiety about the future in the long term, and this decreased work engagement. Understanding the long-term dynamics of teachers’ work engagement in the context of organizational ostracism and future anxiety enhances conceptual and practical understanding of this issue.</p>