This research examines the impact of the COVID‐19 pandemic on labour market outcomes of union workers, based on nationally representative data. I employ the difference‐in‐difference estimation to identify the effect of the COVID‐19 pandemic on the employment, labour earnings and other labour market outcomes of union workers, relative to non‐union workers. I find that, compared to non‐union workers, union workers experienced greater job security, and the pre‐pandemic union wage premium remained largely unchanged during the pandemic. There exists a large heterogeneity in the union effect on employment and real wages by worker characteristic. I also find that union workers, compared to non‐union workers, were less likely to work remotely but more likely to receive pay for hours not worked due to COVID‐19. The results suggest that unions provided workers with employment stability and an economic buffer during the pandemic‐led recession.