This study aims, through an interdisciplinary approach, to investigate the concept of social justice in the political thought of Imam Ali (peace be upon him) and to examine its relationship with certain contemporary theories of justice. The main research question addressed in the present study is: “What are the foundations and indicators of social justice in Nahj al-Balagha from the perspective of Imam Ali (peace be upon him), and how do these indicators relate to contemporary theories of social justice?” Accordingly, the study employs qualitative content analysis and comparative methods, drawing upon primary Islamic sources—particularly Nahj al-Balagha—as well as the works of thinkers such as John Rawls, Robert Nozick, and Amartya Sen. The findings indicate that justice, from Imam Ali’s perspective, is grounded in principles such as the oneness of God, intrinsic human dignity, rejection of discrimination, protection of the rights of the disadvantaged, and the accountability of rulers, all of which were realized in his practical governance. Comparative analysis with contemporary theories of social justice reveals that, despite certain similarities, there are fundamental differences in epistemological and anthropological foundations: Ali’s conception of justice is rooted in theology and ethics, whereas modern theories primarily rely on social contracts and secular frameworks. The study’s novelty lies in integrating Islamic sources with contemporary theories to propose a contextually grounded and inspirational model of social justice, capable of addressing inequalities and injustices in modern societies. This research thus provides a basis for constructive dialogue between Islamic political thought and contemporary social justice theories.