"It is a much more sophisticated game. I can imagine it being quite addictive viewing. This kind of programme is the future of television and the future of game shows.
Charles, who also presents BBC Two's Robot Wars, replaces Ulrika Jonsson, who was forced to pull out after health concerns over her unborn baby.
Channel 5's Jailbreak features contestants in a mock prison who can win £100,000 if they escape.
The project, which has already been criticised by prisoners' groups, gets under way on Sunday when 10 of the 35 shortlisted candidates are "arrested" and taken to the "prison".
Big Brother rival
Liverpudlian Charles, who first made his name on the comedy stand-up circuit, described the concept as "more exciting" than Big Brother.
"It is a much more sophisticated game. I can imagine it being quite addictive viewing. This kind of programme is the future of television and the future of game shows.
"It is very realistic. To all intents and purposes it is a proper jail," he added.
The "prison", at a secret location near Potters Bar, Hertfordshire, is kitted out with hi-tech security systems, but it will be possible to escape.
"Inmates", who face a three-week authentic prison regime, will have to evade 35 prison guards and a 18-foot high fence topped with razor wire to escape.
'Chinks' in security
"There are some chinks in the armoury but obviously we are not going to tell the contestants where they are," said Jailbreak's executive producer Sebastian Scott.
Viewers will follow the participants plotting to escape from the open prison regime via 35 cameras.
The show will be broadcast round-the-clock on a website, with viewers encouraged to email contestants with escape tips.
The production team will pass five of the best messages a day to each contestant, and advice that helps escape will earn the emailer 10% of the jailbreaker's prize money.
Teamwork
"It is about a combination of skill. Will it be the oldest and wisest person or the youngest and fittest person who gets out?" Scott asks, adding: "Will they work together to escape?"
The rules of the game say contestants may escape in groups up to three, with the prize money divided among them.
After the first escape the award for breaking out reduces on a sliding scale.
Jailbreak starts on 12 September and will broadcast live from the prison at 1900BST every evening except Saturday.