This paper examines the evolution, scope, and consequences of judicial activism in transforming India’s penal system into a rights-oriented and reform-driven framework. Judicial activism has played a transformative role in shaping modern penology in India by expanding the scope of constitutional protections and redefining the philosophy of punishment. Through progressive interpretations of fundamental rights under Articles 14, 19, and 21 of the Constitution, the Supreme Court of India has shifted the focus of the criminal justice system from retributive justice to reformative and rehabilitative approaches. Landmark decisions such as Maneka Gandhi v. Union of India, Hussainara Khatoon v. State of Bihar, and Sunil Batra v. Delhi Administration have strengthened prisoners’ rights, ensured speedy trials, prohibited custodial torture, and emphasized humane conditions of detention. Judicial interventions have also addressed issues like overcrowding, legal aid, death penalty jurisprudence, and prison reforms, thereby promoting human dignity as a core constitutional value. While critics argue that judicial activism sometimes encroaches upon legislative and executive domains, its impact on Indian penology has largely been progressive, fostering accountability and aligning penal policies with constitutional morality and international human rights standards.