His body was discovered at the property in Green Street, central London, shortly after 10am today. Paramedics were called but he was pronounced dead at the scene. A postmortem has been scheduled but police said his death was not being treated as suspicious. They would not comment on reports he had killed himself.
A spokeswoman for McQueen said: "Mr McQueen was found dead this morning at his home. We're devastated and I hope you understand that out of respect to his family and his colleagues we're not going to be making any further statement."
The death comes days before the start of London fashion week and a month before the designer was to unveil his new collection at Paris fashion week.
His family asked for privacy to come to terms with the death of McQueen, whose first name was Lee.
His company, Alexander McQueen, issued a statement saying: "On behalf of Lee McQueen's family, Alexander McQueen today announces the tragic news that Lee McQueen, the founder and designer of the Alexander McQueen brand, has been found dead at his home. At this stage it is inappropriate to comment on this tragic news beyond saying that we are devastated and are sharing a sense of shock and grief with Lee's family."
"Lee's family has asked for privacy in order to come to terms with this terrible news and we hope the media will respect this."
Tributes quickly poured in after news of McQueen's sudden death.
Alexandra Shulman, the editor of British Vogue, said McQueen had influenced a whole generation of designers. "His brilliant imagination knew no bounds as he conjured up collection after collection of extraordinary designs," she said. "At one level he was a master of the fantastic, creating astounding fashion shows that mixed design, technology and performance and on another he was a modern-day genius whose gothic aesthetic was adopted by women the world over. His death is the hugest loss to anyone who knew him and for very many who didn't."
The designer Katherine Hamnett said: "He was a genius. What a terrible, tragic waste."
Dame Vivienne Westwood said she was "incredibly sorry" to hear the news.
Matthew Williamson said: "I am shocked and deeply saddened by McQueen's death. He was a genius and his talent was second to none. Like many others I always cited him as a hugely inspirational leader of world fashion. He will be greatly missed."
A spokesman for the model Kate Moss said: "Kate is shocked and devastated at the tragic loss of her dear friend Lee McQueen. Her thoughts are with his family at this sad time."
McQueen was praised for raising the profile of British fashion around the world. "Alexander McQueen made an outstanding contribution to British fashion," said the culture secretary, Ben Bradshaw. "His extraordinary talent and creativity mean that his designs are adored not just by followers of haute couture but lovers of great style everywhere. This is a great loss to one of Britain's most successful industries and to the design world more widely."
A spokeswoman for the British fashion council said: "He was a unique talent and one of the world's greatest designers. Our thoughts are with his friends and family at this sad time."
Comments had been posted on McQueen's Twitter page, McQueenWorld, expressing his distress over the death of his mother on 2 February.
He wrote last week: "i'm letting my followers know the my mother passed away yesterday if it she had not me nor would you RIP mumx"
A minute later he added: "but life must go on!"
On Sunday McQueen wrote: "sunday evening been a f****** awful week but my friends have been great but now i have to some how pull myself together..."
Born in London in 1969 as the youngest of six children, McQueen left school at the age of 16 and was offered an apprenticeship at the traditional Savile Row tailors Anderson and Shephard, then at neighbouring Gieves and Hawkes.
At 20 he was employed by the designer Koji Tatsuno. A year later McQueen travelled to Milan where he worked as a design assistant to Romeo Gigli. He returned to London in 1994 where he completed a master's degree in fashion design at Central St Martins College. His degree collection was famously bought in its entirety by Isabella Blow, a leading figure in the fashion world who died in 2007.
In less than 10 years McQueen became one of the most respected
fashion designers in the world. In October 1996 he was appointed chief designer at the French label Givenchy where he worked until March 2001.
In December 2000, 51% of Alexander McQueen was acquired by luxury brand Gucci, where he became creative director. Expansion followed and included the opening of flagship stores in New York, London and Milan.
McQueen was a four-time winner of the British designer of the year award as well as the international designer of the year award from the Council of Fashion Designers
