Background <p>Poor physical function in older patients with pre-dialysis chronic kidney disease (CKD) is a significant concern, as it affects their prognosis. This study investigated factors associated with poor physical function in this population, including geriatric syndrome, renal function, and anemia.</p> Methods <p>This cross-sectional study included 142 patients aged ≥ 65&#xa0;years with stage 3–5 pre-dialysis CKD who were admitted for CKD education. Physical function was assessed using the Short Physical Performance Battery (SPPB), with scores of 12 points defined as normal group and scores ≤ 11 points as low physical function. Furthermore, the number of medications, Geriatric Depression Scale-5 (GDS-5) and Lubben Social Network Scale-6 (LSNS-6) scores, nutritional indices, renal function, and anemia were assessed.</p> Results <p>A total of 62 (43.7%) patients exhibited low physical function. GDS-5 and LSNS-6 scores, number of medications, exercise habits, and age significantly differed between the normal group and low physical function group (<i>p</i>&#xa0;&lt;&#xa0;0.05). Multivariate analysis revealed that GDS-5 score (odds ratio [OR]: 1.65, 95% confidence interval [CI]: 1.11–2.45) and number of medications (OR: 1.27, 95% CI: 1.09–1.46) were significantly associated with low physical function after adjustment for age, sex, body mass index (BMI), diabetes mellitus, hemoglobin (Hb), estimated glomerular filtration rate (eGFR), and Geriatric Nutritional Risk Index (GNRI) (<i>p</i>&#xa0;&lt;&#xa0;0.05), while LSNS-6 did not demonstrate a significant association.</p> Conclusions <p>Poor mental health and a high number of medications may be key factors contributing to low physical function in older patients with pre-dialysis CKD.</p>