The study investigates the relationship among perceived failure of the performance appraisal purposefulness, the injustice perceptions, in-role performance and retaliation in Public sector of Pakistan. The overall injustice perception serves as mediator among the performance appraisal purposefulness failure and in-role performance and retaliation. Whereas the study perceived organizational support tests as moderator between performance appraisal purposefulness failure and Overall injustice perception. The study gathered data using a self-administered questionnaire from 400 civil servants across 12 occupational groups appointed in major cities of Pakistan, from which 380 responses seems to be valid with a 95% response rate. The study uses a time-lag design to collect data at two different times (time 1 and time 2). The responses on in-role performance and retaliation was reported by peers. Amos 20 and Process 3.0 were used for data analysis. The results confirm a positive relationship between performance appraisal purposefulness failure with retaliation but for in-role performance, a negative relationship was not found. However overall injustice perception found to be positively related with in-role performance and retaliation level. The results also show that overall injustice perception partially mediates the relationship between the failure of performance appraisal purposefulness and the in-role performance, but no mediation was found among retaliation. The study also confirms the moderation of Perceived organizational support. The research results have practical and practical significance for civil servants and public organizations in the new geographical environment. This study is a rare attempt to test all aspects of performance appraisal purposefulness failure and overall injustice perception on the in-performance and retaliation.