Major League Baseball is entering the prediction-market arena, announcing a multi-year partnership that designates Polymarket as the league's official prediction market exchange and includes a new integrity-focused agreement with federal regulators.

Financial terms were not released, but Polymarket is believed to pay MLB around $300 million over three years as part of the agreement, with the per-year amount potentially closer to $150 million, according to Front Office Sports.

The Polymarket deal gives the platform and its brokers exclusive rights to use MLB marks and logos inside prediction-market products, along with access to official league data through Sportradar, MLB's global distributor for prediction markets.

MLB is the latest league to lean into the fast-growing prediction-market space, joining a group that already includes the NHL, MLS and UFC. The NHL has officially partnered with both Polymarket and Kalshi, while Polymarket has also secured separate agreements with MLS and the UFC.

MLB said the centerpiece is an integrity framework designed to limit what can be offered, including working with Polymarket to restrict markets the league views as higher risk, such as contracts tied to individual pitches, manager decisions, or umpire performance and requiring integrity controls to be built into Polymarket's U.S. rulebook so brokers operate under the same standards.

"Polymarket is about bringing fans closer to the moments that define sports," Polymarket founder and CEO Shayne Coplan said. "By working collaboratively with Major League Baseball and regulators, we can create new ways for fans to engage with the game while protecting the integrity of the sport."

At the same time, commissioner Rob Manfred signed a memorandum of understanding with Commodity Futures Trading Commission (CFTC) chairman Michael S. Selig that establishes regular communication and confidential information-sharing related to baseball integrity and prediction-market activity. MLB framed the move as a continuation of its push for guardrails, noting it urged the CFTC a year ago to adopt strong protections as the space grows.

"The new agreements that we formed with Polymarket and the CFTC are imperative steps in proactively managing the new and rapidly growing prediction market space," Manfred said. "Protecting the integrity of the game on the field is our top priority."