The BBC production took the prize for best drama series, and Martin Freeman was awarded best supporting actor for his role as Watson, alongside Benedict Cumberbatch's Holmes.
The show beat rivals including ITV1's Downton Abbey, BBC3's Being Human and E4's Misfits.
Sherlock, based on Arthur Conan Doyle's Sherlock Holmes stories, was launched last summer and became a huge hit, despite running to only three episodes. New shows are now in production.
Mike Gatiss, the writer and co-creator of the modern-day adaptations, said: "It's a huge honour and a fantastic surprise. Thank you so much, it's a huge thrill."
The new media prize went to Wallace And Gromit's World Of Adventure, beating online spin-offs and apps for the BBC's Brain Test Britain, The Thick Of It and Misfits.
Another winner at the awards at London's Grosvenor House was the BBC1 film Between Life And Death, named best single documentary.
Presenter Graham Norton raised a laugh as he lined up the International TV Show award when he joked about the recent recruitment of Cheryl Cole, from Newcastle, for the US version of X Factor.
"Just because a programme has subtitles doesn't mean it can't be successful - just look at Cheryl Cole on American X Factor."
The prize went to Danish crime drama The Killing.
Celebrity chef Hugh Fearnley-Whittingstall's campaigning Channel 4 series Hugh's Fish Fight took the best features prize. The show aims to raise awareness of dwindling fish stocks and beat Come Dine With Me, Mary Queen Of Shops and Pineapple Dance Studios.
Surprise winner of the best comedy prize was BBC2's Harry And Paul - stars Paul Whitehouse and Harry Enfield did not even attend. Norton was among the winners, taking best entertainment performance for his chat show The Graham Norton Show.