"They gave me the highest evaluation and are a world-famous team." Tanaka said at a news Thursday after agreeing to a $155 million, seven-year deal with the Yankees.
Tanaka said he was "relieved" the deal was done and looked forward to standing on the mound at Yankee Stadium.
Asked what his goal will be, Tanaka's response was direct: "To become world champions."
In addition to the deal with Tanaka, the Yankees must pay a $20 million fee to his Japanese team, the Rakuten Golden Eagles over the next 18 months.
His agreement calls for $22 million in each of the first six seasons and $23 million in 2020, and it allows him to terminate the deal after the 2017 season and become a free agent.
Asked to deliver a message to Yankees fans in English, Tanaka said he plans to let his performance on the field do the talking.
"I don't speak English so I'll just have to win the trust and confidence of the fans with my performance on the field," the 25-year-old right-hander said.
His agreement was front-page news in New York, where the Daily News devoted the top half of its front page to a photograph of Tanaka's pop star wife Mai Satoda in a bikini with the headline: "Yanks score a Ta-knockout."
Big league teams had until Friday to reach an agreement with Tanaka, who was 24-0 with a 1.27 ERA last year as the Eagles won the Japan Series title. The Arizona Diamondbacks, Chicago Cubs and White Sox, the Los Angeles Dodgers and Houston Astros all said they were among the failed bidders.
Tanaka said he consulted with 2013 Rakuten teammate Takashi Saito and Texas Rangers pitcher Yu Darvish about life in the major leagues before deciding on the Yankees.
"Everything will be new and challenging," Tanaka said. "But I have to rely on the ability that got me this far."
Tanaka was 99-35 with a 2.30 ERA in seven seasons with the Eagles, striking out 1,238 in 1315 innings. Yankees official has tracked him since 2007, scouting 15 of his games.
The Tanaka deal caps an off-season in which the Yankees added catcher Brian McCann and outfielders Jacoby Ellsbury and Carlos Beltran. The four big deals totalled $438 million.
"We're going to do what we've got to do to win," Yankees co-chairman Hank Steinbrenner told The Associated Press in a telephone interview. "We had to make sure we had enough pitching to go together with our new lineup."
Tanaka receives the highest contract for an international free agent and the fifth largest deal for a pitcher, trailing only those of the Los Angeles Dodgers' Clayton Kershaw ($215 million), Detroit's Justin Verlander ($180 million), Seattle's Felix Hernandez ($175 million) and the Yankees' C.C. Sabathia ($161 million under his original agreement with New York).
Tanaka replaces the retired Andy Pettitte in the Yankees rotation, and joins Sabathia, Hiroki Kuroda and Ivan Nova.
New York owes half the $20 million to Rakuten within 14 days, another 17 per cent within six months, an additional 17 per cent within a year and the final 16 per cent within 18 months.
AP Sports Writer Ronald Blum in New York contributed to this report.