McCann has passed his physical and the final language of his five-year, $85 million contract -- which includes a vesting option for $15 million for a sixth season and a no-trade clause -- was agreed upon and signed.
In a statement, owner Hal Steinbrenner said the Yankees are just getting started.
"The singular and unwavering desire of this organization is to construct a team each and every season designed to play meaningful baseball deep into October," Steinbrenner said. "In Brian McCann, we feel we have made a significant improvement to a key position, while adding a high-character presence to our clubhouse.
"Our work this offseason has just begun, but we feel this is an important step towards what will be an exciting and rewarding 2014 season for our fans."
There is no word as to what number McCann will wear with the Yankees. He wore No. 16 for the Atlanta Braves, but that number is retired for Whitey Ford.
McCann will replace Chris Stewart, who was traded to the Pittsburgh Pirates on Monday, as the Yankees' starting catcher. The Yankees feel McCann's left-handed swing is perfectly suited for the short porch in right field in the Bronx.