While deplatforming has become an increasingly common strategy to combat online harm and far-right extremism, its effects on the followers of extremist groups—who are key supporters and play a crucial role in spreading and sustaining these ideologies—remain underexplored. On August 10, 2018, Twitter (now X) deplatformed one such far-right extremist group, the Proud Boys, along with their affiliated accounts. Leveraging this intervention, our research addresses a key knowledge gap by examining the impact of deplatforming on the cohesion of extremist group followers. Specifically, we investigate whether deplatforming leads to fragmentation or reinforces unity among the group’s followers. We assess cohesion through three theoretical lenses: task commitment, social commitment, and sense of belonging. By analyzing over 12 million tweets from approximately nine thousand Proud Boys supporters between August 1, 2017, and September 1, 2019, we find that deplatforming had a limited effect on reducing group cohesion. Instead, it may have prompted followers to seek broader networks and external interactions, leaving overall cohesion largely intact. This study offers important insights into the resilience of online extremist communities and the limitations of deplatforming as a strategy to disrupt them. Understanding these dynamics is essential for developing more effective approaches to counter online extremism and promote safer digital spaces.