Background: Knee osteoarthritis is a highly prevalent chronic condition that affects approximately 80% of individuals aged ≥ 65 years. Major problems include pain, dysfunction, reduced quality of life, balance ability, and muscle tone. Objects: This study examined the effects of multidirectional knee-strengthening exercises using elastic bands on knee pain, functional disability, quality of life, balance ability, and rectus femoris (RF) muscle tone in elderly patients aged ≥ 65 years with knee osteoarthritis. Methods: Forty-eight patients aged ≥ 65 years with knee osteoarthritis participated in the study. The participants were assigned randomly to either the experimental group (n = 24) or the control group (n = 24). Both groups performed knee-strengthening exercises, but the experimental group incorporated elastic bands into their exercises. All interventions were conducted 3 times a week for 30 minutes per session over 4 weeks. The effects were assessed before and after the intervention using the Numeric Rating Scale (NRS), Korean version of the Western Ontario and McMaster Universities Arthritis Index (K-WOMAC), Euro Quality of Life 5 Dimension (EQ-5D), Berg Balance Scale (BBS), and RF muscle tone. Between-group differences before and after the intervention were analyzed using the independent t-test, and withingroup differences were examined using the paired t-test for pre-post intervention comparisons of the dependent variables. Results: Both groups showed significant improvements in the NRS, K-WOMAC function, KWOMAC total score, EQ-5D, BBS, and RF muscle tone after the intervention (p < 0.05). In addition, the experimental group showed significant improvements in the NRS, K-WOMAC, BBS, and RF muscle tone compared with the control group (p < 0.05). Conclusion: Multidirectional knee-strengthening exercises using elastic bands can be an effective intervention to improve knee pain, functional disability, balance ability, and RF muscle tone in elderly patients aged ≥ 65 years with knee osteoarthritis.