The show's producers have signed up the 53-year-old businesswoman for the 11th series of the BBC Two show.
Kelly Hoppen, who was awarded an MBE in 2009, runs her own firm as well as a design school and is famed for her use of taupe and beige colour schemes.
She has alsofronted a Channel 5 series; Superior Interiors, 37 years of experience in the design industry, runs the Kelly Hoppen Design School, written a number of books and used to date former Tottenham and Arsenal footballer Sol Campbell.
Producers are still to appoint a further Dragon after Theo Paphitis and Hilary Devey left the show.
She started her career at the age of 16, when she designed a family friend's kitchen. She is also an ambassador for the Prince's Trust and the Prince's Initiative for Mature Enterprise.
"I have always been passionate about championing entrepreneurs, so being able to take it to the next level by investing my money in innovative new businesses is very exciting," said Hoppen.
"Having started my design business as a teenager, building a global brand through two recessions, I understand the reality of running a creative business.
"I'm looking forward to bringing a different perspective into the Den and to hopefully finding an undiscovered gem or two!"
Dragons' Den exec Ceri Aston said: "Kelly is an exciting addition to the Dragons' Den line-up. With her creative energy, business acumen and acute sense of style, she embodies everything that's great about British design. I'm thrilled to have her on board."