Studies on the concept of social justice in the Qur'an are still dominated by fragmentary or normative-theoretical approaches that do not touch on applicable constructions based on social reality. This study aims to construct a theory of Qur'anic social justice through an integrated approach, namely thematic interpretation (mawḍū‘ī) and the Constructive Grounded Theory (CGT) method, in order to produce an understanding of social justice that is integrative, adaptive, and relevant to contemporary social challenges. With a qualitative approach, primary data in the form of Qur'anic verses related to social justice (Q.S. Asy-Shura: 15; An-Nisa: 58; Al-Hadid: 25; An-Nahl: 90; Al-Hujurat: 13; and others), as well as secondary data from interpretation literature and socio-Islamic studies. The analysis was carried out through the CGT stages, including initial coding, focused coding, theoretical coding, and theoretical reflection. The research results show that social justice in the Qur'an encompasses four main pillars: (1) the theological foundation of justice as an individual and collective mandate; (2) the priority and purpose of social justice as an indicator of the excellence of the community and a guardian of human dignity; (3) the mechanism for implementing justice through amar makruf nahi munkar, da'wah, and structural reform; (4) the threat of injustice that triggers social slander, disintegration, and moral crisis. This study confirms that upholding social justice from a Qur'anic perspective requires an integration of spiritual awareness, social reconstruction, and collective participation based on the values of revelation. This research contributes to the development of Qur'anic Science and Tafsir and provides an applicable theoretical model for building a just, equal, and dignified Muslim society in the contemporary era.