How do labor organizations with a movement orientation arise in an authoritarian regime? How do they organize workers collectively in a repressive society? What movement roles do they play? What challenges do they face? To answer these questions, I use synthesized social movement theories to examine movement-oriented labor non-governmental organizations in China. Based on qualitative data collected through triangulated sources, I find that movement-oriented labor non-governmental organizations use political opportunities to promote one type of modular collective labor action, which consists of three tactics, namely the election of worker representatives, collective negotiation, and protest. They guide workers to build mobilizing and connective structures, formulate collective action frames, and amass movement resources. However, the movement roles of this type of labor non-governmental organization have weakened, owing to diminishing political opportunities caused by changes in government administration. This research contributes to our understanding of social movement theories, labor organizations in China, labor non-governmental organizations and worker centers generally, and state–society relations in non-democracies.