"Beyonce has been advised by her doctors to rest as a result of dehydration and exhaustion and will not be able to perform in Antwerp, Belgium tonight," the venue said in a statement posted on its website.
It added that the singer was "awaiting word from her doctors before making a decision" on her second Antwerp performance scheduled for Wednesday.
Representatives for Beyonce said in a statement that the canceled concert would be rescheduled as soon as possible and "other tour dates are not expected to be affected."
The cancellation comes after multiple media outlets speculated over the weekend that Beyonce, 31, may be pregnant with her second child.
The "Single Ladies" singer is currently on the Europe leg of her "The Mrs. Carter Show World Tour," part of her return to music after taking a year off following the birth of daughter Blue Ivy, the first child for Beyonce and her rapper-husband, Jay-Z.