Objective: To test the validity, reliability, and acceptability of the Oxford Knee Score (OKS) Mandarin Chinese version for measuring knee pain and function among Chinese breast cancer survivors. Methods: This validation study was a secondary analysis of a cross-sectional survey that was conducted at the Affiliated Hospital of Southwest Medical University, Sichuan, China. Recruited from a larger arthralgia-related survey cohort, those who experienced knee arthralgia and completed the OKS Chinese version were selected for the current analysis. The Cronbach's alpha coefficient was calculated to identify the internal consistency reliability of the OKS. Spearman's correlations were adopted to identify the concurrent validity of the OKS. The discriminate performance of the OKS via subgroup analysis of breast cancer survivors with or without arthritis, as well as different exercise levels, cancer stages, chemotherapy protocols, and occupations, was also conducted. Results: One hundred and fifty-nine breast cancer survivors were included. There were significant correlations between the OKS and the FACT-B, the SF-36, and the BPI in measuring knee pain symptoms and their impact on daily living activities. The Cronbach's alpha for the OKS total scores was 0.90. The participants with arthritis reported significantly lower OKS scores than those without arthritis (P = 0.040). The difference in OKS total scores between the participants with different exercise levels (P < 0.001) and the participants with different occupations (P = 0.006) was statistically significant. Considerable ceiling effects (>15%) of the OKS Chinese version were found in 11 of 12 items. Conclusions: The OKS Mandarin Chinese version is a short, valid, reliable, and sensitive tool for knee pain and function assessment among breast cancer survivors.