He said: "This was not an easy decision for me to make, and in truth it will never feel like the right time to leave a company like Sainsbury’s. It has been a privilege to have led the Company for the past 10 years and I am incredibly proud of our achievements in that time."
He will be replaced by the current commercial director Mike Coupe. He said: "It's an absolute honour to be appointed as the new CEO of Sainsbury's in this, the Company's 145th year, and at a time when thanks to Justin's leadership, we have been consistently outperforming the market.
"I very much look forward to building on that success for our customers, colleagues, suppliers and shareholders."