Knee stiffness is a common and debilitating condition resulting from various etiologies, including trauma, surgery, and degenerative diseases. It can present itself in three different forms: lack of extension, lack of flexion, and a mixture of both. Arthroscopic treatment has emerged as a minimally invasive and effective option for addressing knee stiffness, offering significant advantages over traditional open surgery. This chapter explores the classification, the indications, the surgical techniques, and the outcomes associated with arthroscopic arthrolysis. Key procedures include arthroscopic lysis of adhesions, synovectomy, and manipulation under anesthesia, all aimed at restoring range of motion and function. The success of arthroscopic treatment is influenced by factors such as the duration and severity of stiffness, underlying how the patient’s adherence to postoperative rehabilitation protocols is paramount. Studies consistently demonstrate improvements in pain, mobility, and overall knee function following arthroscopic intervention, with a lower risk of complications compared to open procedures. Future research should focus on refining surgical techniques, developing standardized rehabilitation protocols, and identifying predictors of success to enhance the efficacy of arthroscopic treatment for knee stiffness. This chapter analyzes the current practice of treatment of knee stiffness and highlights the importance of a multidisciplinary approach in managing this challenging condition.