In this study, the objective is to analyze the efficacy of different aquatic physical exercise programs in the treatment of osteoarthritis in older people. The systematic review was conducted until April 2024 and updated in November 2024 in five electronic databases. Randomized controlled studies in people over 60 years of age with a diagnosis of osteoarthritis were included. Water-based exercise interventions were assessed for their impact on osteoarthritis symptoms, walking ability, muscle strength, depressive symptoms, range of motion, body composition, fear of falling, fall risk, quality of life, range of motion, and dual task function. The methodological quality of included studies was assessed using the Physiotherapy Evidence Database. A total of 12 studies were included, with sample sizes ranging from 35 to 312 participants. The presence of osteoarthritis in the sample was manifested in different joints. The methodological quality of the included studies varied from fair to good. Based on the results of this review, aquatic exercise significantly improved balance, stiffness, pain, and walking ability compared to non-exercise controls ( < 0.05). Compared with land-based exercise groups, only one study found significant differences between the two groups. Water-based exercise programs do not provide significantly superior benefits compared to other exercise modalities and appear to have limited effectiveness in the management of OA. However, the feasibility and high adherence make these programs a recommendable option for older people with OA. Future studies should investigate the impact of exercise intensity on the short- and long-term efficacy of aquatic therapy.