Nowell, who featured at the last two World Cups, has only played in the Champions Cup for Exeter Chiefs since the end of March and the 30-year-old said he will take some time off before his expected move to European champions La Rochelle next season.
"No World Cup, I'm not doing the World Cup. I am just going to chill. I need to get my knee sorted," Nowell told the RugbyPass Offload podcast on Tuesday.
"Obviously, it was a bit of a hard decision not to put myself in for selection for the World Cup. I thought it was probably one I had to make for myself and my family as well."
Nowell, who has 46 caps, has not been called up to the England squad since new coach Steve Borthwick took over from Eddie Jones.
England, 2003 World Cup winners and finalists four years ago, begin their campaign in France on September 9 against Argentina. Their Pool D opponents also include Japan, Samoa and Chileck.
