The 21-year-old's previous deal at the Ricoh Arena had been due to expire at the end of the current campaign.
However, having established himself as manager Tony Mowbray's number one keeper this term, Charles-Cook has now committed himself to Coventry until the summer of 2018.
"I've been delighted with Reice this season, on and off the field, and he is fully deserving of his new deal," Mowbray told the club's official website.
"There is still more improvements for him to make and by no means is he the finished product, but I'm sure with the hard work he puts in and with Lee Burge continuing to push him every day in training, the club is very healthy at the moment with two excellent young goalkeepers."
Charles-Cook, who started his career as a trainee with Arsenal, joined the Sky Blues in 2014.