The Daily Telegraph’s former fashion editor was described as “one of the brightest and kindest people in the business” and “always on top of her game”.
Alexander died on Sunday on her 77th birthday, as reported by the Telegraph.
Born in New Zealand, Alexander moved to the UK in 1982, writing for the Telegraph’s women’s page.
She would stay at the publication for 26 years, becoming fashion editor in 1985 and fashion director in 2003.
Alexander was twice named journalist of the year at the British Fashion Awards, in 1997 and 2003 respectively.
Writing on Instagram, Furnish, who is married to Sir Elton John, wrote: “So sad to hear of the passing of the great @hilaryalexanderobe.
— Lorraine (@reallorraine) February 6, 2023
“As Fashion Editor for the @telegraph, Hilary was one of the brightest and kindest people in the business.
“She was always so generous with the coverage she gave our @ejaf fundraiser White Tie & Tiara Ball. Condolences to her family and friends.”
Kelly, who worked with Alexander throughout her career, said: “This is desperately sad news.
“I loved having #hilaryalexander on the show – wise, kind and always on top of her game.”
Both the Telegraph and British Vogue posted lengthy obituary tributes to Alexander, hailing her as a “prolific reporter and writer who epitomised the fashion-loving, dizzy industry doyenne”.
Julia Robson, who was her deputy when she was fashion director at the Telegraph, said Alexander had reportedly been the first to coin the expression “supermodel”.
“Hilary, a self-confessed workaholic, was a blur of activity living a life dedicated to her craft,” she wrote for British Vogue.
Fellow broadcaster Shelagh Fogarty wrote: “Hilary was a great guest on air and went out of her way to help me when I saw a gorgeous dress in her reports on London Fashion Week.
“I wondered if I could afford it. She put me in touch with the young designer and it’s been my ‘go to’ ever since.”
Alexander received an OBE in the 2013 Birthday Honours for services to fashion journalism.