Baseball superstar Shohei Ohtani has confirmed he is to join the Los Angeles Dodgers on a record-breaking contract after ending his six-year spell with the LA Angels.

The 29-year-old Japanese free agent's representatives say he has agreed a $US700 million ($A1.1 billion) 10-year deal which would make him the highest earner in Major League Baseball (MLB) history.

Ohtani ended fevered speculation over his destination in a social media post on Saturday night.

The extent of the deal was revealed in a statement from his agent Nez Balelo, which described the move as a "unique, historic contract for a unique, historic player".

While the Dodgers have not made an official statement, their website carried headlines saying it was 'Sho Time' and describing the deal as a '700m stunner'.

MLB posted on social media that 'Hollywood just added another star'.

Ohtani is unusual in that he plays as a pitcher and a hitter, becoming regarded as one of the best in the game on both sides of the ball since his Angels debut in 2018.

He won his second American League MVP award in 2023, despite an elbow injury which curtailed his season and will prevent him from pitching in 2024.

"To all the fans and everyone involved in the baseball world, I apologize for taking so long to come to a decision," Ohtani wrote on his official Instagram account.

"I have decided to choose the Dodgers as my next team.

"First of all, I would like to express my sincere gratitude to everyone involved with the Angels organization and the fans who have supported me over the past six years, as well as to everyone involved with each team that was part of this negotiation process.

"Especially to the Angels fans who supported me through all the ups and downs, your guys' support and cheer meant the world to me.

"The six years I spent with the Angels will remain etched in my heart forever.

"And to all Dodgers fans, I pledge to always do what's best for the team and always continue to give it my all to be the best version of myself.

"Until the last day of my playing career, I want to continue to strive forward not only for the Dodgers, but for the baseball world."

The previous record contract in MLB was the $US426.5 million the Angels paid to outfielder Mike Trout as part of a 12-year deal in 2019.

Kansas City Chiefs NFL quarterback Patrick Mahomes' 10-year $US450 million extension, agreed in September, was the previous highest in US sports.