This study presents a longitudinal analysis examining the process by which the Transport Workers Union (re)established its legitimacy through an integrated strategy encompassing comprehensive campaigns in road transport, aviation, and the gig economy in Australia. We reveal how unions can gain pragmatic legitimacy through power recomposition, moral legitimacy through moral framing, and cognitive legitimacy through the shaping of assumptions. We reveal the systematic transfer of proven strategies to different parts of the industry, adapting to specific conditions and audiences. Our findings provide a framework for unions to revitalize their influence within a dynamic industrial relations landscape.