In this Essay, I defend the broad prohibition of cyber-vigilantism, and argue that well-intentioned private actors can accomplish their goals by working with governments. I first review global jurisprudence, case studies, and academic commentary to explain why courts and policymakers historically have disfavoured vigilantism in other contexts, and I apply that reasoning to cyberspace. I explain that cyber-vigilantism can lead to several negative consequences, including the potential for abuse of the system, undercutting the legitimacy of democratic systems, and disproportionate punishments that are not necessarily effective. I then argue that instead of operating independently, these private groups can more effectively collaborate with governments and other private actors to fight threats in cyberspace.