Oliver had hit out at Sainsbury's after executives turned down an invitation to be interviewed for a special TV programme on the issue of battery hen farming, on 'Jamie's Fowl Dinners'.
He said: "The question is why didn't they come. What is there to hide? It is shocking that the people I work for didn't turn up on the day."
King, who was speaking on Radio 4's 'Today' programme this morning, said that Oliver had written a letter to Sainsbury's staff to say he was impressed with what the company was doing on the issue of chicken welfare. He urged people to watch the programme, which will air tomorrow night on Channel 4 at 9pm.
The supermarket has also used a quote from Oliver in a new ad campaign for its chickens, saying Sainsbury's has "the most to be proud of on this important animal welfare issue".
Asked about Sainsbury's relationship with Oliver, King said: "We're very happy with Jamie. I mean, he's someone who's got an independence of mind and that independence of mind is actually a great benefit to Sainsbury's.
"It means when he speaks on our behalf, when he says positive things about us, people believe him because they know he's also prepared to criticise when he doesn't agree."
Sainsbury's released Christmas trading figures today, showing that like-for-like sales for the quarter were up by 3.7%, excluding fuel. The company said that as well as a strong Christmas sales period, Halloween and bonfire night sales had improved.
Shares in the company were trading up by 4.5% this morning, at 381.5p, an increase of 16.5p.