Polymarket Becomes MLB’s Exclusive Prediction Market Partner

Major League Baseball (MLB) on Thursday named Polymarket its official prediction market exchange partner and signed a memorandum of understanding (MOU) with the Commodity Futures Trading Commission, marking the regulator’s first such agreement with a major U.S. sports league.

Under the partnership, Polymarket and its brokers will receive exclusive access to MLB marks and logos, official league data and brand exposure across the league’s digital ecosystem and live events.

The deal centers on an integrity framework that restricts markets deemed to pose manipulation risk, including contracts on individual pitches, manager decisions, and umpire performance. Polymarket will also integrate those controls into its U.S. Rulebook so that all of its brokers are held to the same standards.

The MOU formalizes a commitment to share information confidentially, with designated representatives meeting regularly to discuss threats to the integrity of MLB games and the broader prediction market landscape. The agreement comes a year after MLB wrote to the CFTC calling for stronger integrity protections in the space.

While Polymarket holds exclusive rights, MLB said it intends to maintain integrity relationships with all other prediction market exchanges offering baseball contracts, requiring each to integrate protections into their own rulebooks.

MLB joins a growing roster of leagues embracing prediction markets. The National Hockey League struck multiyear deals with both Polymarket and Kalshi last October, while Major League Soccer announced its own Polymarket partnership in January.

Prediction Markets Go Mainstream

The partnership caps a remarkable ascent for Polymarket, which runs outcome tokens as ERC-1155s on Polygon and has evolved from a niche DeFi protocol into a mainstream news source.

As The Defiant reported in December, onchain prediction market monthly volumes have grown 130-fold since early 2024, reaching more than $13 billion, making the sector one of the fastest-growing in finance.

Polymarket received CFTC approval to operate in the U.S. in November 2025, and its return followed a $2 billion strategic investment from Intercontinental Exchange, the owner of the New York Stock Exchange. The platform has since rolled out its U.S. app, beginning with sports markets.

The MLB deal also arrives against a complex regulatory backdrop. Just last week, the CFTC issued an advance notice of proposed rulemaking signaling its intent to build a comprehensive framework for prediction markets.

At the same time, state regulators continue to push back. Arizona’s attorney general filed criminal charges against rival platform Kalshi just two days before the MLB announcement, alleging it operates an illegal gambling business in the state. The tug-of-war between federal and state oversight remains unresolved, as the CFTC has argued that prediction market contracts should be classified as derivatives under federal oversight, while some state gaming regulators insist they constitute gambling subject to state-level regulation.