Horrocks also referred to New Broadcasting House, W1 as 'the world's newsroom', explaining it is 'the largest in the world outside China'
In a speech to the World Media Summit in Russia, Peter Horrocks said: "If we want our news to be believed, we need to get our audiences to share it. If they believe us, they will share it."
He said the BBC's standard is now to ask "do you trust our news enough to share it with your mother, brother, or friend?".
During the keynote speech in Moscow, Horrocks also warned of an "unprecedented global threat to impartial and independent news" and called on authorities worldwide to protect the rights of journalists to report freely.
He also reported on the online successes of the BBC World Service, which has suffered cuts in language services and staff.
"The BBC World Service has recently undergone a process of major reorganisation. It has brought the BBC World Service fully into the digital age. Language services such as BBC Russian, BBC Mundo and BBC Chinese became online only operations. At the same time we remain totally committed to serving the substantial audiences receiving us on traditional shortwave radio."
He said that the BBC Russian Service's website has "more than doubled in size in the last year to 1.9 million".
"Already our investments in new platforms have led to an increase in our audience figures – 239 million around the world, up from 225 million last year."
He said that "the increase has been driven primarily by our coverage of the Arab spring".
"BBC Persian TV has doubled its reach in Iran to 6 million, despite facing a campaign of intimidation and censorship by the Iranian authorities. This is the kind of censorship and intimidation that a media summit such as this should unite to deplore."
Horrocks also spoke of how the BBC "is handling the changes the internet is bringing".
"The international news media is going through a revolution that puts the audience in charge. It is a convulsion that is testing every news organisation. With web, social interactivity and globalisation, news brands are in a battle for attention and trust."
He spoke of how the BBC "believes it can succeed just as well in this new world" and explained the BBC's understanding of the "seismic changes and the rapid reforms we are undertaking".
"Gone are the days when audiences were content to only listen to what we produced for them. Social media engagement, with the increasing use of mobile technology, Twitter, Facebook, Skype, means that ordinary people now have the ability to break news faster than journalists and file the first pictures when an event happens. They are able to engage with their peers in commenting. They are performing much of the role that in the past only powerful media organisations could."
He said that BBC research shows that "the fear of social media that characterises so much of the debate at this summit is completely misplaced".
"Some speakers here have criticised social media for being more inaccurate than traditional media or said that it is 'socially irresponsible'.
"But the BBC's research in the UK and around the world indicates that audiences trust the news their friends and family share with them via social media far more than the news they get from most traditional media.
"So, if we want our news to be believed, we need to get our audiences to share it. If they believe us, they will share it."