"I couldn't be more excited for the opportunity," Greenberg said Thursday afternoon.
Beaned by the first pitch he saw in the majors in 2005 while with the Chicago Cubs, Greenberg returned to the majors this past season, signing a one-day contract with the Miami Marlins, who gave him one at-bat in a game against the New York Mets on Oct. 2.
Greenberg, 31, struck out on three pitches against eventual NL Cy Young Award winner R.A. Dickey. At the time of the game against the Mets, Greenberg said he had hopes of a career comeback.
Earlier this month at the winter meetings, Greenberg took a step toward that goal, meeting with Orioles manager Buck Showalter, general manager Dan Duquette and special assistant Brady Anderson.
Greenberg, who hasn't been with a major league organization since 2008, played for Israel in the qualifying round of the World Baseball Classic earlier this year.
An outfielder, Greenberg made his big league debut with the Cubs in Miami on July 9, 2005, and was hit by a pitch thrown by Marlins left-hander Valerio De Los Santos. He suffered a concussion that caused vision problems, vertigo and headaches lasting hours at a time, and it was nearly two years before he regained full health.
Information from ESPN The Magazine's Buster Olney and The Associated Press was used in this report.