May has headed comms at Centrica for more than five years, having joined from publisher Reed Elsevier Group in 2006.
Her departure comes as the firm brings in a new corporate structure, which will result in cuts of about 20 per cent to its comms operation. Centrica plans to decentralise its comms teams into its constituent business units - British Gas, Centrica Energy and Direct Energy - as it looks to reduce costs across the business.
May commented: 'The company wants to take a very different approach to having a centralised comms function.
'I looked at the new structure that we were trying to deliver and it seemed like the obvious point in time to move on and try something different.'
Centrica CEO Sam Laidlaw said in an email to staff that May had 'transformed the corporate affairs agenda' since joining the firm.
May plans to take a break from the corporate world and launch a food business alongside her husband in the New Year.