Ex-contestants including winners Sophie Reade and Brian Belo, Nikki Grahame, Alex Sibley, Charlie Uchea and Stuart Hosking will be working at the restaurant chain on Thursday night for children's charity Barnados.
Series eight winner Belo said: "I've worked with Barnados since winning Big Brother three years ago. I have a longstanding relationship with them and it is a cause that is close to my heart.
"Nando's is one of life's passions and I can't think of anything better than combining raising money for my favourite charity and indulging in my top eatery with some of my Big Brother pals."
All the ex-housemates will be briefed on health and safety and given uniforms before being let loose on the public at 6.30pm. Nando's is taking bookings for tables at the event and will also be open for walk-ins.