The teams announced the deal hours before their three-game series opener in Seattle. Moving from one clubhouse to another, Ichiro started in right field in place of the injured Nick Swisher and batted eighth for New York on Monday night. It was the first time Ichiro, who had spent his entire major league career with the Mariners, started a game batting anywhere other than the top three spots in the lineup.
Fans at Safeco Field gave Ichiro a 45-second standing ovation when he came to bat with one out in the third inning. He doffed his helmet and bowed twice to the crowd before hitting a single and stealing second base. The 10-time All-Star went 1-for-4 and caught the final out of New York's 4-1 victory.
Ichiro, 38, is in the final year of a five-year, $90 million contract. During a news conference to announce the deal, Ichiro acknowledged that he requested to be traded, saying that it was in his best interest to not return to the rebuilding Mariners in 2013.
"When I spent time during the All-Star break to think, I realized that this team has many players in their early 20s," Ichiro said through a translator. "I began to think I should not be on this team next year. I also started to feel a desire to be in an atmosphere that I could have a different kind of stimulation than I have right now."
The Mariners granted Ichiro's request in sending him to the first-place Yankees, who boast the majors' best record at 58-38 and own a seven-game lead atop the American League East standings.
"I'm going from a team having the most losses to a team with the most wins, so it's been hard to maintain my excitement," he said.
Ichiro figures to provide a significant boost to the Yankees, who have been searching for outfield depth since likely losing left fielder Brett Gardner to an elbow injury for the remainder of the season.
"It's been unexpected, sort of out of the blue," Yankees shortstop Derek Jeter said. "That's why you don't ever listen to rumors. Getting someone like this is unbelievable."
Although Ichiro has played the majority of his career in right field, Yankees manager Joe Girardi said the team's primary plan is to use the veteran as a replacement to Gardner in left field. Ichiro said he hasn't played in left field since the 2001 playoffs.
"We're very excited to have him," Girardi said. "We feel that he brings a speed element, a tremendous hitter. That speed element is something that we lost when (Gardner) had surgery. So this is a big day for us."
Ichiro is a career .322 hitter and a former AL MVP, and holds the record for most hits in a season. He had batted over .300 in every season until dipping last year.
The only thing missing on Ichiro's résumé is an appearance in the World Series, and he may get a chance with the Yankees. Ichiro was the AL MVP and Rookie of the Year in 2001 after a stellar career in Japan, and the Mariners reached the AL championship series that season before losing to the Yankees. Seattle has not been back to the playoffs since then.
New York outfielder Raul Ibanez, a former Mariners teammate of Ichiro, said the trade came as a complete surprise to the Yankees clubhouse.
"Nobody in here really knew anything about it," said Ibanez, who has served as the Yankees' primary left fielder during Gardner's absence. "I just learned about it when I got here. I think it's a great addition."
The deal marks the end of Ichiro's historic tenure with the Mariners. Major League Baseball's first Japanese-born position player, Ichiro is the Mariners' all-time leader in batting average and hits. He also won two AL batting titles and 10 Gold Glove awards in his 11-plus seasons with the Mariners.
"It is hard for me to concisely express my feelings," Ichiro said. "When I imagined taking off the Mariner uniform, I was overcome with sadness. It has made this a very difficult decision to make."
But the Mariners had been in a delicate situation with Ichiro, who is batting a career-low .261 this season. A longtime star and fan favorite, Ichiro's skills have been eroding, and there had been much debate in the Seattle media whether he would be back next year with the Mariners, a team that is rebuilding with young talent.
"Ichiro knows that the club is building for the future," Mariners CEO Chuck Armstrong said. "He felt that what was best for the team was to be traded to another club and give our younger players an opportunity to develop."
Mitchell, 25, posted a 3.86 ERA in four relief appearances for the Yankees this season.
Farquhar, 25, was claimed off waivers by the Yankees last month. He made three relief appearances with Toronto last season, his only stint in the majors.
Information from ESPNNewYork.com's John Hickey and The Associated Press was used in this report.