Davies and Phil Ford (Sarah Jane Adventures, Doctor Who) have teamed up for the BBC Cymru Wales production, which will follow the story of two 16-year-old schoolboys, who are all that stands in the way of Earth's destruction at the hands of moon aliens.
Tom Clarke and his friend Benny must use science and magic to battle Nekross aliens or face being eaten by the villains.
"Writing for children is the biggest challenge of all and I think CBBC stands right at the heart of broadcasting," said Davies.
"So I'm delighted to launch this show, a true nationwide collaboration - a Salford commission from a BBC Wales team. We're joining genres too - the show's a wild, funny, thrilling and sometimes scary collision of magic and science fiction.
"Wizards have never met aliens before, and when they do, the result is spectacular! The mysterious Nekross know exactly what to do with magicians. Eat them! Let battle be joined!"
CBBC controller Damian Kavanagh commented: "This is going to be an incredible rollercoaster ride of an adventure. We believe children deserve the best and we're delighted to be working again with Russell and the talented teams at BBC Wales and FME to bring the story to life."
Davies started his career in children's television with shows such as Children's Ward and Dark Season. He went on to have award-winning success with shows such as Queer As Folk, a revived Doctor Who and Torchwood.
Aliens Vs Wizards will air in the autumn on CBBC.