Ronald Acuña Jr. becomes the first MLB player to partner with Kalshi

Ronald Acuña Jr. has become the first MLB player to enter a prediction-market partnership, signing with Kalshi, according to The Athletic’s Wednesday reporting cited by rg.org. The Atlanta Braves outfielder and former National League MVP adds a player endorsement to Kalshi’s existing relationship with his club.

A commercial featuring Acuña ran Wednesday night during Game 4 of the Braves’ National League Division Series against the Los Angeles Dodgers, according to rg.org. Los Angeles won 4-1, securing the best-of-five series 3-1 and ending Atlanta’s season.

Kalshi expands its baseball relationships

The endorsement follows by less than two months Kalshi’s announcement of partnerships with five MLB teams: the Braves, Boston Red Sox, Dodgers, San Diego Padres and San Francisco Giants. According to rg.org, Kalshi is also reportedly discussing a leaguewide agreement with MLB; that potential arrangement is not described as finalized.

The New York Mets and New York Yankees preceded those clubs in partnering with trading platforms, reaching agreements with Novig and Polymarket, respectively. Acuña’s deal extends the sector’s presence in baseball from team relationships to an individual active player.

A new endorsement, familiar scrutiny

Acuña follows other active professional athletes into prediction-market partnerships. According to rg.org, golfer Bryson DeChambeau became the first to partner with Kalshi earlier this year, followed by NBA star Giannis Antetokounmpo and Inter Miami forward Lionel Messi.

The Athletic expects Acuña’s agreement to attract more scrutiny than those endorsements because of MLB’s gambling history and its efforts to distance players from wagering controversies and game fixing. The deal also comes amid state-level disputes involving Kalshi’s sports event contracts, including a $3 million effort against state prediction-market rules that rg.org reported on this week. Prediction markets operate under federal regulation, while US sportsbooks receive licenses state by state, according to rg.org.

What it means for prediction markets

• Player endorsements add another channel for visibility. Acuña’s agreement builds on Kalshi’s five MLB club partnerships, rather than establishing its first baseball connection.
• Leaguewide expansion remains unconfirmed. Reported talks with MLB are distinct from the completed player and team agreements.
• Regulatory and integrity questions remain central. The endorsement brings MLB-specific scrutiny alongside the existing state-level disputes over sports event contracts.