The Athletics selected O'Loughlin's contract from Triple-A Las Vegas on Saturday, Ken Rosenthal of The Athletic reports.
O'Loughlin signed a minor-league deal with the A's during the offseason, and he has put up a 5.12 ERA and 1.62 WHIP across 38.2 innings in Triple-A. Despite his poor performance, he'll join the big-league roster to provide a fresh arm to Oakland's pitching staff -- likely as a multi-inning reliever.