Hammond is currently head of PR/communications for clothing brand Diesel UK, and has previously worked in communications and marketing for Swarovski, L'Oreal Luxury and IPC Media magazine Wallpaper*.
Hammond will be responsible for the day to day running of the magazine and will report to publishing director Linda Swidenbank.
"I'm thrilled to be returning to IPC in my new role as publisher of InStyle," says Hammond. "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."
Publishing director Linda Swidenbank says: "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 takes up her new role on 13 December.