Sainsbury's chief executive of six years, Mike Coupe, is set to step down and retire in May this year.
Coupe will be succeeded by the retail giant's current head of retail and operations, Simon Roberts, on June 1.
The decision comes in spite of the fact that Coupe said he would be staying on last May following a failed attempt at a merger with market rival Asda.
The merger was blocked by the UK competition regulator amid concerns that it could drive up prices for consumers.
Having resisted pressure to relinquish his role after the merger failed, Coupe said that the decision to step down in 2020 had been a "difficult" one to make, but he believed that the time was now right.
He said: "There is never a good time to move on, but as we and the industry continue to evolve, I believe now is the right time for me to hand over to my successor."
Coupe's departure comes after the retailer announced that "hundreds" of management jobs would be offloaded to cut costs following the integration of Argos into the business.
Roberts has been heavily involved in the integration process, with Coupe adding that his experience made him "the right choice" of successor for "our customers, our colleagues and our investors".