Navarro, 25, batted .279/.366/.491 with nine home runs and 35 RBIs in 66 games with Triple-A Indianapolis and .160/.232/.220 with one home run and four RBIs in 29 games for the Pirates last season. He is a career .279/.350/.437 hitter in 536 games over seven seasons in the Minor Leagues.
Medina, 19, went 1-3 with a 4.14 ERA (50 IP, 23 ER) in 11 games between Gulf Coast (10 games) and Class-A Aberdeen (one game) last season.
The Orioles designated right-handed pitcher Stu Pomeranz for assignment to make room on the 40-man roster. The 27-year-old Pomeranz didn't allow a run in 10 Minor-League outings between Double-A Bowie and Triple-A Norfolk in 2012. He pitched to a 3.00 ERA in three games with the Orioles.
The Orioles also agreed to terms for 2013 contracts with Alexi Casilla, Steve Pearce and Taylor Teagarden, avoiding arbitration with the trio.
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, and follow her on Twitter @britt_ghiroli. This story was not subject to the approval of Major League Baseball or its clubs.