The deal was agreed to Dec. 23, but the sides had to complete contract language, and the switch-hitting first baseman and Maryland native had to pass a physical.
Teixeira (Mount St. Joseph) grew up in Severna Park as an Orioles fans, and the Orioles were among a handful of teams, including the Boston Red Sox and Washington Nationals, to go after the free agent this offseason, initially offering a seven-year deal between $140 million and $150 million.
But no serious negotiations between the Orioles and Teixeira's agent, Scott Boras, took place after that proposal was made.
Teixeira, 28, has hit 203 home runs and is a .290 hitter over six major league seasons.
New York has committed $423.5 million to three free-agent additions during the offseason after its streak of 13 consecutive postseason appearances ended. On Dec. 18, the Yankees finalized a seven-year, $161 million contract with left-hander CC Sabathia and a five-year, $82.5 million deal with right-hander A.J. Burnett.
The news conference will be one of the final events at the old Yankee Stadium. The team will move into the new $1.3 billion Yankee Stadium, across 161st Street, next season.