The 33-year-old, cut from the South Africa squad on Thursday because of a broken hand, told a news conference: "I always made it my intention that I would retire after the World Cup.
"This is a bit premature but, unless something else happens to someone else down the line, then yes, this is it."
Rhodes, regarded as the best fielder in the world and a highly effective middle-order batsman, was dropped by the selectors after it was revealed his hand would take at least three weeks to heal, ruling him out of the first round of the tournament.
"It is not quite the script that I envisaged," he said, but added: "I actually really see it as a blessing. When I left school in 1988, there wasn't really a hope for me to play.
"I saw one of the newspaper headlines, it said 'broken dream', but for me to have played 245 one-day internationals and participated in four World Cups, there's nothing to be ungrateful for.
"It's been a privilege to play for my country."
Rhodes is due to play for English county Gloucestershire later this year.
South Africa will call up batsman Graeme Smith as a replacement once they have been given the go-ahead by tournament organisers.
The International Cricket Council, phoned by Reuters, confirmed that it was technically possible for Rhodes to be recalled later as an injury replacement if another South Africa squad
DEFINITE PLANS
Rhodes said: "I'm going to play cricket in the UK for six months. I'm going to take it one season at a time but I have no definite plans.
"Everyone keeps saying you've got to get back to cricket and cricket has brought a lot of joy for me but I'd also like to think, over the last 14 years of first-class cricket and 10 years for my country, that I've given back a bit as well.
"I don't feel the need to put anything back into the game, although obviously I'm going to encourage as many kids as possible to play.
"I don't think I've got the patience to be an umpire or the temperament to be a coach, and I'm not a commentator. I may talk a lot in the field, but it's mostly rubbish," Rhodes added
"Maybe I'll take up surfing, it's safer out there."
Rhodes's exit came two days after Shane Warne, the game's most successful leg spinner, pulled out of the World Cup after failing a drugs test.
Rhodes, his country's most capped player in one-day internationals, suffered the injury while trying to take a catch during South Africa's 10-wicket win over Kenya in Group B on Wednesday.
Rhodes, also a hockey international, retired from Test cricket in 2000 to concentrate on one-dayers and to spend more time at home with his wife and daughter.
He played 245 one-day internationals and 52 tests, averaging just over 35 in both. His last Test came in August 2000.