St Peter's Collegiate Academy, on Compton Road West, donated Caribbean food to The Good Shepherd charity after the cancellation on Friday.
The issue was identified on Thursday night but by then it was already too late to cancel the caterers who had been booked for the event, chiefs said.
But rather than have the food go to waste, the school instead donated the portions of food including jerk chicken, rice and peas and curried goat to the charity.
Principal Tim Mullen-Furness said: “Whilst we know our students are disappointed that we have had to postpone the event until next week, the safety of our students and staff always comes first.
"We are so pleased that the food from today has gone to a good home and will be enjoyed by people in need.”
A spokesman for The Good Shepherd, which aims to end homelessness in the city, said: "We are so thankful to St Peter’s for thinking about us when trying to find a home for the food from their event. It will be a real treat for our service users.”