The Action Comics writer's six-issue series focuses on the British equivalents of Batman and Robin.
The characters are members of the International Club of Superheroes, a concept revived in recent years during Grant Morrison's run on Batman.
"I'm delighted to be working in DC Britain," Cornell told The Source.
"Grant always said that he added something to the Knight and Squire's world with every appearance. We'll be taking that policy, and the amount of over the top weird and wonderful zany surreal Britishness, and dialling them up to eleven.
"If you've wanted to see a milkman fighting a dinosaur in a suit, in a pub, then this is the comic for you."
Cornell - who was recently revealed to have signed an exclusivity deal with DC - is working on the series with artist Jimmy Broxton.