The 26-year-old was one of seven to be dropped, with Michael Dawson, Leighton Baines, Scott Parker, Tom Huddlestone, Adam Johnson and Theo Walcott also omitted.
Bent was handed a final chance to impress manager Fabio Capello in Sunday’s 2-1 win over Japan but was substituted at half-time.
The Black Cats striker insists he will closely follow England at the World Cup before turning his attentions to doing his best for Sunderland next season.
He told the club’s official website: "I feel really disappointed. I've always said to myself - if you play well and do your best for Sunderland then there's a chance you can go to the biggest tournament in the world. But obviously on this occasion it hasn't worked out."
"Straight away from when Mr Capello spoke to me and told me I wouldn't be involved in the 23-man squad, my thoughts turned to next season and how I can improve on what I've done for Sunderland this past year.
"I'm going to take some time off now and rest my bones after what's been a great season for me and get ready for next year. It's just a case of fully concentrating on my football for Sunderland and doing my best for them.
"Of course I still want the boys to do well. I've got a lot of friends in the England set up. They're a great bunch of lads and even though I won't be there, I'll be supporting them."
Despite scoring 24 Premier League goals last season, Bent was not expected to be named in Fabio Capello’s World Cup squad after the Italian had favoured Wayne Rooney, Peter Crouch, Jermain Defoe and Emile Heskey throughout qualifying.
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