Background: Assessment of work performance (AWP) is a test for assessing work performance and can be utilised in matching person-work and applying effective interventions. It was aimed to adjust and to evaluate the validity and reliability of AWP in Turkish with individuals with mild intellectual disability (ID). Methods: The study was conducted with 243 individuals with mild ID. Of the 243 participants, data gathered from 105 individuals was used to conduct exploratory factor analysis (EFA) and remaining data (138 individuals) was used to conduct confirmatory factor analysis. Internal consistency, construct validity, test-retest reliability, criterion-related validity and inter-rater reliability were analyzed. Results: The AWP showed average to good reliability for individuals with mild ID. The construct validity and internal consistency of the AWP were confirmed with satisfying results; test-retest reliability (ICC >0.92) and inter-rater reliability (ICC >0.90) were excellent for all domains. The EFA resulted three factors, explaining 66.46% variance; and CFA resulted average fit. Conclusion: AWP is valid and reliable for evaluating the working performances of individuals with mild ID.