Hammond replaces Inca Waddell, who was promoted from acting publishing director at InStyle in January this year. Wadell has left to return to her home country of South Africa.
Hammond has previously worked for IPC as head of marketing for Wallpaper. She has also worked as a senior PR manager at L'Oreal Luxury and as marketing and communications director of Swarovski. She leaves her current job as head of PR and communications for Diesel UK.
In her new role, Hammond will report to publishing director, women’s lifestyle, Linda Swidenbank. She will take up the position on 13 December.
Swidenbank said: "Sarah is steeped in the world of luxury fashion and she will be a fantastic asset to the team. It's great to welcome her back to IPC Southbank and I look forward to working with her to continue InStyle's upward momentum."
Hammond said: "I'm thrilled to be returning to IPC in my new role as publisher of InStyle. 2011 is a hugely exciting year for the magazine as it celebrates its 10th anniversary in the UK and I join at a time where the editorial content is stronger than ever."
InStyle, which has been under the editorship of Eilidh MacAskil since February last year, was up 1.8% year on year with an average net circulation of 186,251 in the latest ABCs for the six months to June 2010.