Annarose Bridal Boutique decided to donate the 20 dresses after being asked for one to be showcased in a fashion show at the city's Queen's Hotel.
The dresses, which have never before been worn by brides, will then go on sale at the fashion show and at Shelter Scotland shops.
John Sinclair Shelter Scotland shops regional manager, said: “When we were organising our fashion show we thought it would be a dream come true to be able to top it off with a wedding dress. When Annarose came back to say we could have 20 it was unbelievable.
“The dresses are of extremely high quality and mean that some lucky brides can have a beautiful gown at a bargain price, knowing that they are helping people escape the misery of homelessness at the same time.”
Anne Elder, owner of Annarose Bridal said: “As a bridal boutique owner I get to see people prepare for one of the happiest days of their lives. It is lovely to be able to contribute to people who face some of the toughest challenges – like not having a home at all or having one they can’t rely on.”
The Shelter Scotland fashion show takes place at the Queen’s Hotel on 30 October.