Philip Treacy le Bon, Kate Moss, Christy Turlington and Stella Tennant modelling in return for keeping Treacy's hats, which were all black. In 1994, he opened up his boutique at 69 Elizabeth Street, in Belgravia, London, right beside Isabella Blow's resicence at number 67. Treacy has designed hats for Alexander McQueen (another discovery of Isabella Blow), including his 1999 "white collection" for Givenchy Haute Couture in Paris, for Karl Lagerfeld at Chanel, and for Valentino, Ralph Lauren, Donna Karan, Versace and Rifat Özbek. In January 2000, he became the first milliner for 80 years to be invited to exhibit at the Paris
Patrick Treacy in Cork in 2005. In April 2016, the High Court in Dublin granted a possession order over Treacy's clinic buildings in favour of a bank-appointed receiver. In June 2016, Treacy made a €137,897 settlement with the Irish Revenue as a result of unpaid taxes, interest and penalties. Treacy met Michael Jackson in 2006 after Jackson sought him for cosmetic treatment after reading about his experience with HLA fillers and his charitable work in Africa. He was Jackson's personal dermatologist and developed a friendship with the singer. Treacy and Jackson worked on humanitarian projects together. In 2011, Treacy became an ambassador