Mr Clarke said that he will be succeeded by incoming chief operating officer Roger Burnley, who will join the Leeds-based company in October, adding that the pair will at first spend time together before he hands over the reins.
Mr Clarke told trade magazine Retail Week: “I said that I wanted to find somebody who had the ability to be my successor and it took us some time to find the right person, the right cultural fit, the right sort of character and leader that can run the business. He’s a great leader and he’s going to be a great colleague.
“I look forward to spending time with him and preparing him for what hopefully should be his next role.”
Asda poached Mr Burnley from rival Sainsbury’s last year, where he was retail and operations director. He also did a stint at Asda between 1996 and 2002, when he was supply chain director.
However, Mr Clarke did not give a time frame for his departure, adding: “I’m in no rush to do anything else and we are on a three-year journey from a strategic plan perspective. I’m very happy to deliver that and work through that and then we can talk about that from there.”
In May, Asda revealed another hefty sales slump as it reported the seventh consecutive quarter of sliding sales.
The chain posted a 5.7 per cent fall in like-for-like sales for the 13 weeks to March 30, showing little improvement on the 5.8% drop seen in its Christmas quarter, which was its biggest quarterly sales fall on record.
The chain said it remained focused on its revival plan, dubbed Project Renewal, which involves pumping £500m into cutting prices for shoppers in a fightback against its Big Four rivals and discounters Aldi and Lidl.
Last week, Walmart International’s chief executive Dave Cheesewright raised the prospect of further price cuts - saying that the US giant would look to “shift the balance in Asda from protecting profit to protecting share”.