Chavez passed his physical after agreeing to terms over the weekend and is officially a member of the organization.
Chavez, who turns 34 in February, batted .301/.323/.426 with five home runs and 27 RBIs in 83 games with the Texas Rangers this year. He's a career .274/.313/.373 hitter in 10 major league seasons.
"Endy is a tremendous defender and gives us needed depth in the outfield," executive vice president Dan Duquette said in a statement. "He is a veteran player whose left-handed bat will give us options off the bench."
The Orioles' 40-man roster is full. They'll have to designate someone to clear room for their next acquisition.