Misinformation thrives on social media, prompting much research into social media interventions such as debunks. This paper tests debunking’s effectiveness against an understudied but prominent form of online misinformation: misleading organizational claims of corporate social responsibility, or CSR-washing. British participants ( N = 657) took part in a preregistered experiment with a 2 (debunk: present, absent) x 3 (CSR-washing: greenwashing, bluewashing, purplewashing) between-subjects design. They saw an Instagram ad from a fictional clothing company that showcased its dedication to environmental sustainability, gender equality in the workplace, or the elimination of child labor. Half of the participants then received a debunk. Unlike most previous research which showed continued influence of misinformation after debunking, we found that the debunks were very effective: they reversed the persuasive effects of CSR-washing, resulting in negative brand attitudes and low purchase intentions. Several explanations for this finding are discussed, highlighting CSR-washing’s distinctiveness from many other forms of misinformation.