The latest monthly distributive trades report found more shop owners thought sales would rise over the next three months than fall, giving a balance of plus 25, the highest figure since May 2002. The survey also found sales growth this month rose at the fastest pace in six months, with a balance of plus 37.
Supermarkets, chemists and carpet and furniture stores experienced the strongest growth, with specialist food and drink stores seeing the steepest fall.
A balance of plus 10 of retailers placed more orders with their suppliers than a year ago, although this was just below expectations of plus 13.
Employment grew in the sector over the year, at plus 12, the fastest rate since November 2013. CBI deputy director general Katja Hall said: "The high streets have been bustling with shoppers this summer."