The Los Angeles Dodgers have finalised their 12-year deal with right-handed pitcher Yoshinobu Yamamoto, teaming the prized free agent with Shohei Ohtani in their prolific winter spending spree.

The Dodgers didn't disclose the value of the deal they announced Wednesday, but several media reports have tagged it at US$325 million. That would be the largest and longest contract ever guaranteed to a major league pitcher.

The 25-year-old Yamamoto has been Japan's most dominant pitcher over the past few seasons, and he was coveted by teams across the majors after he elected to leave the Orix Buffaloes this offseason.

The big-budget, pitching-poor Dodgers landed him with another mammoth December deal after signing two-way AL MVP Ohtani to a US$700 million contract and signing right-hander Tyler Glasnow to a US$136.5 million, five-year deal after his acquisition from Tampa Bay.

“I’d like to thank everyone in the Orix organisation, the Dodger organisation and all the people close to me who have given me so much support throughout this free-agent process,” Yamamoto said in a statement.

“I am truly excited to wear Dodger Blue and can’t wait to play in front of a packed Dodger Stadium.”

The Dodgers are getting a 5-foot-10 right-hander widely regarded as the world's best pitcher outside North America — and one with potential to become a major league ace after a stellar start to his career in Japan. (AP)