According to MLB, Marcano did not appear in any of the games on which he placed bets as his Pirates-related wagers occurred after he suffered a season-ending knee injury last July.
"The strict enforcement of Major League Baseball's rules and policies governing gambling conduct is a critical component of upholding our most important priority: protecting the integrity of our games for the fans," MLB Commissioner Rob Manfred said in a statement.
"The longstanding prohibition against betting on Major League Baseball games by those in the sport has been a bedrock principle for over a century.
"We have been clear that the privilege of playing in baseball comes with a responsibility to refrain from engaging in certain types of behaviour that are legal for other people."
According to data obtained from a legal sports betting operator, MLB concluded that Marcano placed 387 baseball bets, including 231 MLB-related wagers from October 16th to 23rd, 2022 and from July 12th, 2023, through November 1st, 2023.
In total, MLB said Marcano bet more than $150,000 on baseball, with $87,319 of that on MLB-related bets.
MLB also said there is no evidence to suggest - and Marcano denies - that any outcomes in the baseball games on which he placed bets were compromised, influenced, or manipulated in any way.
Marcano first signed with San Diego as an amateur out of Venezuela in 2016 and made his MLB debut in 2021, appearing in 25 games for the club that season before being traded in July of that year to the Pirates.
Marcano had surgery to repair a torn right anterior cruciate ligament that he sustained last July when he awkwardly stepped on third base during a game.
The Padres selected Marcano off waivers last November but he had not played for the team since being acquired.
Oakland Athletics pitcher Michael Kelly was also suspended one year for betting on MLB games while he was playing in the minor leagues.
In addition, MLB said minor league players Jay Groome (Padres pitcher), Jose Rodriguez (Philadelphia Phillies infielder) and Andrew Saalfrank (Arizona Diamondbacks pitcher) were each banned one year for betting on MLB games.
