The move comes with Houston looking to rebound from a 9-4 loss on Friday as it continues the series at home.
Brian McTaggart of MLB.com reported the transaction, noting that Houston designated right-hander J.P. France for assignment to clear a roster spot.
Harris is batting .250 with three hits, one RBI, two runs and two stolen bases this season.
The addition comes after Harris had spent time with the White Sox, giving the Astros another outfield option as they adjust their lineup.
The Cardinals series continues at Minute Maid Park, and Houston hopes the roster shakeup helps them keep momentum at home.
Overall, the Astros’ front office has balanced immediate needs with upside, adding Harris while moving France off the active roster.