Global supply chains (GSCs) have become an integral part of the global economy, changing the patterns of trade, investment, and production in global industries. While the rise of GSCs poses new opportunities and challenges to workers, its impacts have yet to be fully understood. Building on a growing body of literature on GSCs and labour standards, this paper examines how the emergence and change of the fragmented cross-national production system affects social upgrading in developing countries, focusing on the impact of private governance on labour conditions and workers’ rights. It discusses emerging trends in GSCs during the post-crisis period and their impacts on social upgrading, highlighting the unevenness of social upgrading and the role of global buyers in the differentiation of labour conditions among workers. The paper discusses the role of private voluntary standards in governing labour relations in GSCs, and their limitations and tensions with buyers’ purchasing practices. It concludes with a discussion of the future of labour governance in GSCs in terms of improving the effectiveness of private governance and building a complementary and synergistic relationship across private, public and social governance for sustainable economic and social upgrading in GSCs.