Unsustainable HR practices impose illegitimate tasks on employees due to a shortage of resources. These illegitimate tasks bring counterproductive work behavior in terms of workplace incivility that creates a sense of ostracism in employees. To address these issues, the study examined the relationship among unsustainable HR practices in terms of illegitimate tasks and workplace ostracism. Whereas workplace incivility is defined as an underlying reason through which this association exists. Adopting a theoretical framework from earlier research, the study used cross-sectional data (...) and subsequently a method of quantitative research, and the sample comprised permanent faculty members of private universities in Pakistan working in different departments with different role titles. Smart PLS was applied to run multiple statistics analyzed on the obtained data. The results from the study supported the hypothesis by depicting a positive and significant association between illegitimate tasks and workplace ostracism. Further, workplace incivility was playing the mediating role between illegitimate tasks and workplace ostracism. The results from the study carry significant implications for managers and researchers. Recommendations and future research directions are also discussed in the paper. (shrink)