Tony Hall has taken the helm of the BBC and spoken of the "enormous responsibility" he faces as director general.
Lord Hall, who began as a BBC trainee 40 years ago, started work at 8.30am and has been meeting staff at the corporation, which has seen its reputation battered after the Jimmy Savile sex abuse scandal.
Speaking outside the new Broadcasting House in central London, Birkenhead-born Lord Hall said: "It's exciting for me to be coming back to where I started my career in the BBC. It's an enormous responsibility being the sixteenth director general of the BBC, but it's also something I am very excited about and feel very privileged about.
"I have spent a lot of time over the past weeks, especially over the last weekend, watching and listening to a huge number of programmes and services and content, and I take my hat off to the people working in this place.
"What we produce here is extraordinary and distinctive and very, very wonderful. I'm very, very proud indeed to be leading the BBC from this moment on."
The former chief executive of the Royal Opera House was offered the job after George Entwistle stepped down after 54 days in November when Tory peer Lord McAlpine was wrongly implicated in child abuse claims on BBC2's Newsnight.
Lord Hall, who was made a cross-bench peer in 2010, also faces low morale at the broadcaster after staff went on strike last week over jobs, workload and allegations of bullying. The 62-year-old was the only person contacted by the BBC Trust for the £450,000-a-year post. The new director general was head of BBC news and current affairs from 1996 to 2001.
Media commentator Raymond Snoddy - a former presenter of the BBC News Channel's NewsWatch - has warned he will have "a honeymoon period - but it could be a short one".
He said: "Tony Hall arrives with an ocean of good will behind him as the 'right person' to sort out the mess the BBC is in following the Savile and Newsnight scandals. He will soon be judged on how well he succeeds - or not - in improving trust in the BBC and restoring morale while coping with real falls in income."
On announcing senior appointments in February, Lord Hall admitted that "there is a lot of hard work ahead" and that he hopes to "define the BBC and public service broadcasting for the next decade".