This article examines the evolving legal nature of corporate social responsibility (CSR) in the European Union (EU), focusing on the textile, clothing, leather and footwear (TCLF) sector. Analysing legal and policy developments, it argues that the legal architecture of CSR has become pluralistic and hybrid. Once conceived as voluntary conduct beyond legal mandate, CSR is undergoing a “hardening” through which soft-law norms and societal expectations crystallise into binding obligations. Frameworks from legal sociology and regulation studies – legal pluralism, reflexive law, autopoiesis, meta-regulation and the regulatory trilemma – illuminate this shift. The analysis highlights EU initiatives such as the Corporate Sustainability Reporting Directive and the Corporate Sustainability Due Diligence Directive, and national laws (France’s Loi de Vigilance, Germany’s Supply Chain Act) that embed CSR into formal legislation. In the TCLF sector, new rules compel firms to internalise social and environmental responsibilities across their supply chains. This hybrid governance seeks to strengthen accountability while preserving flexibility. CSR in the EU has no single doctrinal source or fixed legal status; it exists at the dynamic interface of hard and soft law across global, regional and national levels, raising key questions about normative coherence and the role of stakeholders in enforcing corporate accountability.