Introduction <p>The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is a key patient-reported outcome measure designed to evaluate pain, stiffness, and physical function in knee osteoarthritis. Translating WOMAC into Kannada language would improve health care and research among Kannada-speaking patients. Hence, the study aimed to translate WOMAC into Kannada version of WOMAC (K-WOMAC) and test its psychometric properties.</p> Methods <p>WOMAC was translated into K-WOMAC using the standard Beaton guidelines, which involved forward and backward translations, a pre-final version review, an expert committee evaluation, and final administration. Fifty individuals with knee osteoarthritis (IKOA) were recruited to evaluate the scale’s reliability and validity. Validation assessments included content validity, construct validity with varimax rotation, concurrent validity with Numerical Pain Rating Scale (NPRS), intra-rater and test–retest reliability, Bland and Altman method, standard error of measurement (SEM) and minimal detectable change (MDC), and floor and ceiling effects of K-WOMAC.</p> Results <p>Scale-level content validity index (S-CVI/Ave) of K-WOMAC is 0.97. The exploratory factors yielded 5 factors with 24 items of cumulative variance contribution rate of 78.7%. Concurrent validity of K-WOMAC with NPRS is ρ (rho) = 0.73; p &lt; 0.001. The intra-rater and test–retest reliability of K-WOMAC are ICC = 0.87 and ICC = 0.65 respectively. Bland and Altman graph confirmed the level of agreement between the sessions. Standard error measurement (SEM) and minimum detectable change (MDC) are observed to be 9.9 and 25, respectively. However, there is no floor and ceiling effect in K-WOMAC.</p> Conclusion <p>English version of WOMAC is translated into Kannada language, K-WOMAC with acceptable psychometric properties.</p>