Palumbo (thumb) was activated off the minor-league injured list and recalled from Triple-A Nashville on Sunday.
Palumbo has been sidelined since Aug. 20 due to a blister on his right thumb, but he's ready to return after throwing a simulated inning Thursday. The 24-year-old had a 2.67 ERA, 0.85 WHIP and 39:10 K:BB in six starts at Triple-A, but he's expected to pitch in 1-to-2-inning stints now that he's back with the Rangers.