The present study examines the effect of service employees’ job insecurity on job performance through emotional exhaustion. We identified workplace incivility (i.e., coworker and customer incivility) as a boundary condition that strengthens the positive relationship between job insecurity and emotional exhaustion. To test this moderating effect, we collected online panel surveys from 264 Korean service employees at two time points three months apart. As predicted, the positive relationship between job insecurity and job performance was partially mediated by emotional exhaustion. Of the two forms of workplace incivility, only coworker incivility exerted a significant moderating effect on the job insecurity–emotional exhaustion relationship, such that this relationship was more pronounced when service employees experienced a high level of coworker incivility than when coworker incivility was low. Coworker incivility further moderated the indirect effect of job insecurity on job performance through emotional exhaustion. These findings have theoretical implications for job insecurity research and managerial implications for practitioners.