As the global economic situation deteriorates due to the prolonged COVID-19 pandemic, the business environment is plagued by uncertainty and risk. To address this, many organizations have sought to optimize efficiency, especially by downsizing and restructuring, to reduce costs. This causes anxiety among employees, who worry about whether they will be fired. We hypothesize that such job insecurity increases knowledge-hiding behavior by employees, and we investigate the mechanism underlying such a negative effect. In addition, we attempt to capture the boundary conditions of how to reduce the adverse effects of job insecurity, focusing on the role of coaching leadership. Using three-wave time-lagged cohort-study data from 346 Korean workers, we empirically found that employees who perceive job insecurity are less likely to feel organizational identification, leading to increased knowledge-hiding behavior. This study also demonstrated that coaching leadership operates as a boundary condition which buffers the negative influence of job insecurity on organizational identification. Theoretical and practical implications are discussed.