The British Red Cross shop in St Benedicts Street had been shut since the fire on February 25.
Staff and volunteers are now welcoming customers once more following extensive repairs.
George Burroughs, shop manager, said: “We would like to say a heartfelt thank you for the outpouring of love and support we have had from everyone.
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“We have a very loyal customer base and people have been in tears over the temporary closure of the shop.
“It has been here for more than 30 years and during that time the community has been very important to us.”
Much of the stock was damaged during the fire and locals are being asked to donate whatever they can, including clothes, shoes, gifts, ceramics and china.
Mr Burroughs added: “The people of Norwich have done so much for us, but we need your help again.
“Please bring us your donations so we can raise money to help others who are in need.”