Research on trade unions in China has commonly pointed to their inefficacy in organising and representing the workers as a formal institutional actor in industrial relations. Few empirical studies have examined the differing role of the unions at various levels during a strike through an in-depth study of the strike process and its settlement. This study addresses this research gap through a case study of a strike that took place in 2010 in a Japanese-funded auto plant in southern China. The paper extends existing knowledge of Chinese labour disputes/relations by highlighting the agency role of union actors at the grassroots level. We argue for a more nuanced view in understanding union officials’ and representatives’ respective roles and agency underpinned by their personal ideology, organisational resources and the broader political environment. These complexities and nuances shape the strike outcomes and the ensuing changes in the labour relations of each case company. This study makes a contribution towards the decent work agenda in China by demonstrating, through empirical evidence, what trade unions can do to help workers improve their employment terms and conditions at the workplace level.