"We've got the prospect of Champions League football to look forward to next season and with the quality of players we have I believe we are on the brink of something big," added King.
"It is an exciting time for the club with a new training ground being built and plans for a new stadium.
"I am enjoying my football and I want to be a part of what is happening here."
King, who has won 19 England caps, missed out on a place in the 2006 World Cup squad because of a broken foot.
But his chances of being selected for Capello's squad for South Africa, which will be trimmed down to 23 players by 1 June, have been boosted because of doubts over the fitness of first-choice central defender Rio Ferdinand of Manchester United, as well as the absence of the injured Manchester City defender Joleon Lescott and United's Wes Brown.
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