The project has created 2,000 jobs
The new Quays project in Gloucester has provided a "fantastic opportunity" for traders across the city, it is claimed.
The £200m designer outlet centre, which opened a few days ago, has already attracted thousands of shoppers.
Gloucester's Federation of Small Businesses says this means more people visiting the city than ever before.
City centre retailers should take advantage of this, see what they can offer and review how they are marketing themselves, the Federation said.
The Quays project features a 60-acre section of the city's quayside turned into shops and flats, with a hotel, supermarket and factory outlets.