Taking over from interim boss Robert Bensoussan, his task will be to boost sales, which dipped slightly to £94m last year.
Mr Bensoussan has been with LK Bennett for eight years and only planned to serve as chief executive until the company found a replacement.
The retailer has 114 shops in the UK and Ireland, including a recently opened concession in Harrods, as well as stores in the US and Middle East.