A class action waiver is a provision found in some contracts which prohibits a party from filing a class action legal proceeding against the other party, or both parties waiving the right to file class actions against each other. Though used internationally, class action waivers, just like class action lawsuits, are predominantly an American phenomenon and most frequently both found and upheld in the United States and agreements with American citizens.

Class action waivers may be found on a standalone basis, though they are more commonly found as part of an arbitration clause, and when paired with such clauses, frequently include jury trial waivers. All three clauses are the subject to controversy and wide legal debate, with supporters claiming the tools are strong risk management tools and the expense that class action litigation presents both in regard to time and money, though advocacy groups argue that these clauses reduce the rights of consumers and employees and prevent companies from being held accountable for grievances such as wage and hour violations.

Class action waivers legality across countries and administrative decisions range in legality between jurisdictions, with some countries like France and administrative divisions like Ontario in Canada banning such clauses, while others, most prominently the United States via its Supreme Court ruling in AT&T Mobility LLC v. Concepcion, have rules that such clauses are enforceable.

A common example of a class action waiver clause is,

We each agree that any dispute resolution proceedings will be conducted only on an individual basis and not in a class, consolidated or representative action.

The Supreme Court of the United States has found on multiple occasions that class action waivers are legal, though in all ruled circumstances on the issue, the Supreme Court has only ruled on class action waivers attached to arbitration agreements. In AT&T Mobility LLC v. Concepcion, the high court ruled that class action waivers are legal under the Federal Arbitration Act as they significantly impact what the court saw as Congress's pro-arbitration stance. The court reiterated its stance in Epic Systems Corp. v. Lewis. In Epic, Justice Neil Gorsuch authored a majority opinion which outlined that the US Congress, upon legislating the National Labor Relations Act of 1935, likely did not wish "to confer a right to class or collective actions in [Section 7 of the NLRA], since those procedures were hardly known when the NLRA was adopted in 1935". Justice Clarence Thomas concurred in a separate opinion, writing that the illegality of the class action waiver is a public policy defense, referring to McMullen v. Hoffman.

Class action waivers in any jurisdiction, however, are not enforceable in cases of sexual assault or sexual harassment; the 117th Congress passed and President Joe Biden signed the Ending Forced Arbitration of Sexual Assault and Sexual Harassment Act in 2022 which additionally prohibited the enforcement of class action waivers. As of 2023, the bipartisan law has been used by employees of companies, most notably Rivian, to sidestep class action waivers. Prior to Epic and AT&T, New York and California have attempted to ban class action waivers, and in the case of California, use such laws to additionally invalidate arbitration agreements or allow judges to refuse to enforce class action waivers in certain circumstances. National lawmakers have also pushed to pass the proposed Forced Arbitration Injustice Repeal Act, which would ban the enforcement of both arbitration clauses and class action waivers in many cases today seen by some as unfair or anti-consumer.

Class action waivers and arbitration agreements have also been argued to be unenforceable by the US Department of Labor, which argued to the Sixth Circuit that the two run contrary to statutory rights with regard to fiduciary misconduct.