Yankees manager Joe Girardi made the announcement after Sunday's 3-2 win over Washington.
''It's good to see'' Girardi said.
Tanaka missed 2 1/2 months last season while rehabilitating a partially torn ulnar collateral ligament in his right elbow. He returned for two late September starts, and Boston chased him with an eight-run second inning in his finale on Sept. 27.
The right-hander threw 23 of 29 pitches for strikes Saturday in a simulated game divided into two innings. The Japanese ace faced nine batters, giving up one single and striking out one.
Signed to a $155 million, seven-year contract in January 2014, Tanaka went 13-5 with a 2.77 ERA over 20 starts.