The 29-year-old royal - who has worn dresses by the British high street store to a number of high-profile events - has been credited with giving the brand a "cooler and sexier" image.
According to accounts filed at Companies House, profits surged to £8.5million from £4.3million in the year to January 31 2011, whilst sales rose to £87.6million from £77.7million.
In addition to Catherine's endorsement of the chain, the family-owned store has also credited the increase in profits to the launch of the Reiss 1971 sub-brand.
The company said in a statement: "The launch of a new sub-brand, Reiss 1971, was the starting point to make the brand much cooler and sexier, to broaden its appeal.
"Every aspect of the brand was appraised, in order to highlight this and to make a more dynamic and sexier statement."
The Duchess of Cambridge first gave the high street store her stamp of approval when she wore a Reiss dress in her official engagement photograph - shot by Mario Testino - with Prince William in January 2011, causing the company's website to crash and it seeing a huge boost in sales from royal fans in the US.
She then went on to wear a cream Reiss dress when she met US president Barack Obama and his wife Michelle, which sold out within hours of the first pictures emerging.