The 13-part drama series is aimed at a post-watershed, adult audience and has been described as a mix between 'X Files' and the mid-1990s drama series 'This Life'.
Former 'Live and Kicking' presenter John Barrowman will reprise the role of Captain Jack, who appeared in the last series of 'Doctor Who'.
Davies said: "'Torchwood' is a British sci-fi paranoid thriller, a cop show with a sense of humour. It's dark, wild and sexy."
Stuart Murphy, BBC Three controller, said 'Torchwood', an anagram of Doctor Who, was a massive coup for BBC Three.
"It's the biggest drama we've ever had on the channel. It introduces a different tone into our drama, just as Russell's 'Casanova' earlier this year brought warmth and humour."
The series is being produced by BBC Wales in Cardiff, as was the last 'Doctor Who', but the storylines from the shows will not cross over.
The second series of 'Doctor Who' is due to air later this year, with 'Casanova' star David Tennant as the Doctor and Billie Piper as his assistant Rose.
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