Lisa Attenborough has been hired to fill the post after spending six years as an interim management consultant.
M&S communications director Flic Howard-Allen, to whom Attenborough reports, said the role would include taking direct responsibility for City and business journalist relationships and managing a 17-strong team, including the corporate press office, corporate events, website work and communications for the annual review.
Howard-Allen said: 'I was looking to put a greater level of expertise in corporate PR.' She added that boosting city links was important now that the business had 'turned the corner' financially.
M&S's financial and corporate agency Brunswick will work alongside Attenborough, who joins on 23 September.
As an interim management consultant Attenborough worked at United Biscuits, Hilton International and most recently at German tech giant Siemens, where she was acting head of corporate comms.
She previously worked in-house at The Financial Times and at consultancy Biss Lancaster.
This is the second senior appointment at the retail giant in the last three months. In June it was announced that former National Magazine company PR head Tania Littlehales had been hired to head PR for its apparel, home and leisure division.
According to documents leaked to PRWeek at the time, Littlehales is responsible for managing a multi-million pound budget and deputising in the absence of Howard-Allen (PRWeek, 7 June).
Siemens is not understood to be looking for a replacement head of corporate communications. However it is on the hunt for a media relations manager.