The announcement comes following a busy period for the UK’s second largest supplier.
Price rises of 9% on average preceded the recent launch of Discount Energy Bonus April 2015 – the cheapest plan on the market.
Deputy chief executive Alistair Phillips-Davies will assume Mr Marchant’s role on 1 July.
Commenting on his departure, Mr Marchant said: “I have been tremendously privileged to be part of a team that has created SSE in to a company with a solid platform for future growth.
“I have thoroughly enjoyed my time as Chief Executive but feel that, after 10 years, the time is right for a change for both SSE and me.
Mr Marchant governed over a successful period for SSE, and was praised by Scotland’s First Minister Alex Salmond, but his tenure since 2002 has also witnessed huge prices rises.
SSE came second in the 2012 uSwitch customer satisfaction survey behind E.ON. It is the first time in the 8-year history of the awards that SSE didn’t win the overall prize.