Background: Knee osteoarthritis (OA) is a degenerative joint disease causing pain, stiffness, and functional limitations, particularly in older adults. Aquatic therapy is emerging as a promising non-pharmacological intervention due to water’s unique properties that reduce joint loading and facilitate exercise. Aim: To review the effectiveness of aquatic therapy on pain relief and functional mobility in individuals with knee osteoarthritis. Methods: A review was conducted analyzing five recent, high-quality randomized controlled trials and systematic reviews published within the last 10 years. Studies were identified through databases such as PubMed and Google Scholar and evaluated for methodological rigor and clinical relevance. Results: Evidence consistently demonstrates that aquatic therapy significantly reduces pain, improves physical function, muscle strength, and balance in knee OA patients. Aquatic cycling and hydrotherapy were particularly effective. Patient adherence and satisfaction exceeded those reported for land-based exercise, making aquatic therapy a viable rehabilitation option. Conclusion: Aquatic therapy is an effective and safe intervention for managing symptoms of knee OA, enhancing quality of life through improved mobility and reduced pain. Future research should focus on long-term outcomes and standardized aquatic protocols.