The aim of this study is to evaluate the efficacy of genicular nerve block (GNB) and intraarticular corticosteroid injection (IACSI) in patients with knee osteoarthritis (OA). Forty patients with Kellgren-Lawrence grade 2-4 knee OA were included for the study. Patients were divided into two groups randomly as IACS and IACS + GNB groups. All patients were evaluated with ultrasound for cartilage thickness, patellar tendon thickness, quadriceps tendon thickness and quadriceps muscle cross-sectional area (QMA). Pain intensity of the patients was evaluated with visual analogue scale and the Leeds Assessment of Neuropathic Symptoms and Signs pain scale. Functional status of the patients was evaluated with Western Ontario and Mc Master Universities Osteoarthritis Index. Quality of life of the patients was assessed with Nottingham Health Profile (NHP). All assessments were measured and compared at baseline, 1st month and 3rd month after treatment. All evaluation parameters were significantly improved in IACSI and IACSI + GNB groups. However, the improvement was better in IACSI + GNB group compared to those in IACSI group in terms of all evaluation parameters except QMA (0.10 ± 0.18 and 0.11 ± 0.22, respectively) and NHP scores in 1st month evaluation (- 3.11 ± 6.99 and - 3.54 ± 1.74, respectively). When combined with IACSI, GNB yields better analgesic effect and improves function in patients with knee OA compared to only IACSI.