Background: Knee osteoarthritis (OA) is a common degenerative joint disorder and a major cause of pain, stiffness, and functional limitation in the elderly. Although multiple conservative treatment options are available, many patients continue to experience significant symptoms. Intra-articular corticosteroid therapy is widely used for short-term symptomatic relief because of its anti-inflammatory action and cost-effectiveness. Objective: To study the clinical and functional outcome of intra-articular methylprednisolone acetate in patients with knee osteoarthritis, with specific evaluation of pain, stiffness, and functional status before and after treatment. Methods: This observational study was conducted in the Department of Orthopaedics, Saraswathi Institute of Medical Sciences, Hapur, after institutional ethical approval and written informed consent. Eighty patients aged more than 50 years with primary knee OA of Kellgren–Lawrence grade II or above were included. Baseline assessment was done using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Patients received an intra-articular injection of 80 mg methylprednisolone acetate with 2% lignocaine through the superolateral patellar approach under strict aseptic precautions. Follow-up was performed at 4, 12, and 24 weeks. Data were analysed using the paired-sample t-test, and p < 0.05 was considered statistically significant. Results: The mean age of participants was 64.84 ± 7.11 years, and females constituted 65.0% of the study population. WOMAC pain score improved from 15.03 ± 2.78 at baseline to 9.26 ± 2.35, 10.07 ± 2.45, and 11.66 ± 2.54 at 4, 12, and 24 weeks respectively. WOMAC stiffness score improved from 5.61 ± 1.11 to 3.50 ± 1.01, 3.91 ± 1.07, and 4.56 ± 1.05. WOMAC functional score improved from 47.39 ± 7.85 to 32.67 ± 5.54, 36.41 ± 5.96, and 41.60 ± 7.19. Total WOMAC score improved from 67.88 ± 8.69 at baseline to 45.33 ± 6.46, 50.20 ± 6.74, and 57.79 ± 7.99 at the respective follow-ups. All improvements were statistically significant (p < 0.001) compared with baseline. No patient was lost to follow-up, and no significant adverse effects were observed. Conclusion: Intra-articular methylprednisolone acetate is a safe, effective, and economical treatment modality for knee osteoarthritis, providing significant short- to medium-term reduction in pain and stiffness with improvement in functional ability. Maximum therapeutic benefit was observed at 4 weeks, though statistically significant improvement persisted up to 24 weeks