The 25-year-old Japanese, who possesses a wicked, diving split-finger fastball, allowed two hits and struck out three after being warmly greeted by the fans when he entered in relief for the fifth inning.
"I was nervous, but it was a really good nervous," Tanaka told reporters, speaking through an interpreter. "It's the first time that the batters faced me. It'll probably be a little bit different the next time around.
"Everything is new to me, so for today, I was just trying to locate my pitches where the catcher was holding his glove."
Tanaka allowed a single to Darin Ruf, the first batter he faced, on an 0-2 fastball but recovered to record two flyouts to left field before striking out a swinging Cesar Hernandez on a 3-2 pitch.
In the sixth, the Japanese right-hander struck out Ben Revere on an 0-2 splitter before Ronny Cedeno blooped a single.
Tanaka, who signed a seven-year, $155 million contract with the Yankees in January, then struck out Domonic Brown and got Kelly Dugan to fly to center field.
Manager Joe Girardi was "encouraged" by what he saw.
"It's the place where he's probably at peace, not having to answer questions," Girardi said.
"He's able to do his work. I think it was important to get under his belt, and the next time will be a start.
"I was encouraged by what I saw; how he handled it. He got in the stretch, gave up an 0-2 hit, it didn't fester. He just went back to work. I thought that was good."
Tanaka, who went 24-0 last season for Japanese league champions Tohoku Rakuten Golden Eagles, crowned a hectic off-season for the injury-hit Yankees, who missed the playoffs in 2013 for just the second time in 19 years.
Tanaka was a key acquisition in the reconstruction of the Yankees' pitching staff following the retirements of Andy Pettitte and closer Mariano Rivera.
They also acquired outfielders Jacoby Ellsbury and Carlos Beltran and catcher Brian McCann among others but lost second baseman Robinson Cano to free agency and third baseman Alex Rodriguez to a season-long doping suspension.
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