Christopher Bailey can design a hemline. His new task is to master the bottom line.

Mr. Bailey, the creative chief at Burberry Group PLC, will become chief executive at the British luxury house next year, the company said Tuesday.

He will succeed Angela Ahrendts, the executive credited with turning around the British brand who is leaving next year to lead Apple Inc.'s retail and online sales operations.

Mr. Bailey will retain his role as designer, putting him in the unusual position of heading both the creative and business sides of a major fashion label.

The move is a risky bet by Burberry's board that the 42-year-old can translate his success on the runway into continuing the rapid sales growth Burberry has enjoyed under Ms. Ahrendts.

Since joining Burberry in 2006, Ms. Ahrendts has reinvigorated the brand, more than tripling sales and presiding over a near-quadrupling of the company's share price. Though he knows Burberry inside and out from his 12 years with the brand -- six years as creative chief -- Mr. Bailey is untested as an executive.

'While Christopher Bailey has proven to be a phenomenal designer, the jury will be out in terms of him running the company as CEO,' said HSBC analyst Erwan Rambourg.

Investors were skeptical, too, sending Burberry shares down 7.6% in London at the market's close. Citi analyst Thomas Chauvet said the CEO change would 'curb enthusiasm' for the company.

Burberry said the board and executive team would bolster Mr. Bailey's creative strengths.

'I am confident that, with [Chairman John Peace's] continued guidance and the executive team's support, Christopher, as one of this generation's greatest visionaries, will continue to lead Burberry to new heights,' Ms. Ahrendts said in a statement.

'It is a complete thrill for me to be able to take that innovation, design and creative head and to marry it with the commerce side of our business to become even more united,' Mr. Bailey said in a video released Tuesday.

Mr. Bailey and Ms. Ahrendts declined to comment further.

Three months ago Burberry finance chief Stacey Cartwright left after nine years to pursue other interests. So far, she hasn't publicly announced a new position. She was succeeded by an internal candidate, Carol Fairweather, who said Tuesday that Mr. Bailey has 'an incredibly sharp commercial mind and he will be supported in his new role both within the existing creative team and workingalongside the management teams that have been in place for a long time now.'

Burberry is one of the biggest businesses in the luxury sector, with more than 500 points of sale globally, from its own boutiques to spaces in department stores. Its products range from its well-knowntrench coats to perfume -- a business that Burberry recently took back in house after years of entrusting it to a license partner.

Mr. Bailey stages four fashion shows a year for the house.

The appointment underscores the changing profile of fashion designers. In the past decade, they have gone from being regarded as frenzied artists to guardians of a brand's image -- in many cases, overseeing everything from clothing and fashion shows to advertising and store design. Yves Saint Laurent designer Hedi Slimane, for example, was given the additional job of supervising all strategic projects at the Parisian label this year.

Two other high-profile designers also occupy the corner office: Ralph Lauren and Giorgio Armani.