French defender Dervite has put pen to paper on a one-year extension to keep him at The Valley until next summer while teenage winger Harriott, the club's young player of the year, has signed a three-year deal.
Harriott, 19, told the club website: "I'm absolutely delighted to sign a new contract
"It was a fantastic season for me and it's great to agree a new deal. Charlton is a great club - I enjoy it here and I love the supporters.
"I'm already thinking about next season, and I want to stay in the team and keep playing as many games as possible."
Charlton had earlier announced that defender Leon Cort had signed a new contract for next season, but striker Danny Haynes is to be released.
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