Objective: The objective of this study was to determine the psychometric properties of the Tinetti Performance-Oriented Mobility Assessment (POMA) scale to measure balance and gait impairments in individuals with knee osteoarthritis (OA). Methods: A convenient sample of 25 individuals with bilateral OA knee were recruited. The convergent validity was determined by correlation analysis between scores of Berg Balance Scale (BBS) with balance subscale (POMA-B) and the Timed Up and Go Test (TUGT) with gait subscale (POMA-G). The intrarater reliability [intraclass correlation coefficient (ICC 3,1)], the Bland–Altman plots limits of agreement (LOA), the standard error of measurement (SEM), minimum detectable change (MDC) and ceiling/floor effects were determined. Results: Score of BBS was significantly correlated with POMA-B scores, rs = 0.63, p = 0.001, whereas TUGT showed a negative correlation with POMA-G, rs = −0.481, p = 0.020, showing moderate convergent validity. ICC results of the total POMA scale (POMA-T), POMA-B, and POMA-G were 0.96, 0.93, and 0.96, respectively, indicating high test retest reliability. SEM, for POMA-T, POMA-B, and POMA-G was 0.35, 0.27, and 0.35, respectively; MDC values were 0.97 for POMA-T, 0.75 for POMA-B, and 0.63 for POMA-G. Conclusion: The findings indicate that the POMA is a valid and reliable tool to assess balance and gait impairments in people with OA knee.