The “Always Be My Baby” singer was scheduled to perform Sunday, which is also her birthday.
“I love my fans in Brussels and at this time I am being advised to cancel my show for the safety of my fans, my band, crew and everyone,” she posted on social media.
It’s unclear whether she plans to reschedule.
Carey, 45, dominated the pop charts in the 1990s, and is one of the best-selling music artists of all time.
Brussels has been on edge since explosions at the airport and subway station killed at least 30 people Tuesday.
Investigators are conducting raids throughout the city in a bid to uncover the network behind the terror attacks.