Celtic chairman Dr John Reid said: "I am delighted to welcome Brian Duffy to the club.
"We have been fortunate over the years to have been able to attract individuals of great calibre and integrity to our board.
"Brian is a long-standing Celtic supporter with a passion for the club, in addition to being a very able businessman and holding a post of great responsibility with one of the world's most prominent luxury lifestyle brands.
"We will be drawing upon his enormous experience in UK and international retail operations, merchandising and brand development as we look to build our business further in the coming years."
Duffy said: "I was brought up in Glasgow and, as a lifelong supporter of the club, I am honoured to join the board of Celtic.
"It is a great privilege to have the opportunity to play a part in the club's future and I am looking forward to it tremendously."