After graduating, Armstrong was offered a job at Elle UK after her freelance writing work was spotted by the then-editor Sally Brampton.
[9] Armstrong used her expertise to argue that this dress, which received a great deal of media attention through being worn by Lopez, Geri Halliwell, and others, represented "some kind of high water mark in the current symbiosis between fashion and celebrity.
"[9] She is known for accessibly written articles which show a keen eye and a sense of wit, and for being unafraid to express controversial opinions, such as criticising the Yves Saint Laurent brand for its multiple name changes.
Armstrong was appointed Officer of the Order of the British Empire (OBE) in the 2022 New Year Honours for services to fashion.
Elle reviewed her first novel, Front Row, as "Has all the juice of a Jackie Collins plus the kind of fash pack details that Armstrong, as fashion features director at Vogue, knows all about.