Thompson was called up from Triple-A Lehigh Valley on Wednesday, Matt Gelb of The Athletic reports.
Thompson will return to the Phillies' bullpen for Wednesday's series finale in order to provide a fresh arm after the club played 16 innings Tuesday. Across six appearances this year, he's logged a 5.54 ERA and 1.46 WHIP. He will likely be utilized as a middle-relief man during his time with the team.