The Athletics selected Ornelas' contract from Triple-A Las Vegas on Friday.
Ornelas recently signed a minor-league deal with the A's, and eight days later he will join the big-league club in Sacramento. The 26-year-old was most recently featured in the majors in 2025 with both Texas and Atlanta. With Joshua Kuroda-Grauer (groin) not due back for some time, Ornelas will provide depth in the middle infield for the Athletics.