King has signed a new four-year contract with the club.
He told the club's website: "I'm absolutely buzzing. To have come so far with the club and to be playing in the Premier League now is a dream come true.
"To be able to commit my future and for the club to have shown this sort of faith in me is a massive boost, so I'm just looking to kick on now.
"I've only ever played for Leicester City and it's looking more and more like they're the only team I'll ever play for. I would love it if that is the case.
"I've always said from when I made my debut against Wolves in 2007 that the fans have been nothing but brilliant with me, so I'd just like to say a big thank you to them."
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