The team announced Wednesday that Correa has been placed on the 10-day injured list. The club called up outfielder Myles Straw from Triple-A Round Rock (Texas) to take Correa's spot on the roster.
"He reported to the stadium and said he had a lot of discomfort in his rib area," general manager Jeff Luhnow said Wednesday.
"Something happened in the morning at his house prior to coming over."
Luhnow would not specify what caused the fracture.
Correa is hitting .295 with 11 home runs and 35 RBIs. He is the sixth Astros player to be placed on the injured list this season.
"The focus is to get him back healthy, help us in the second half and really obviously help in the postseason because that's where we need him the most," Luhnow said.
Correa's last game was Sunday against Boston. He was not in the lineup for the last two games after reporting soreness in his rib cage.