Construction to begin at BBC Wales' Cardiff headquarters
Construction will start on BBC Wales' new headquarters in Cardiff city centre on 7 December.
The announcement followed final sign-offs between the BBC and developers Rightacres.
Almost 1,200 staff will relocate from BBC Wales' current site in Llandaff to Central Square in 2019.
Director of BBC Wales, Rhodri Talfan Davies, said the new development would trigger wider regeneration and help to "change the face of Cardiff".
He added: "BBC Wales touches the lives of millions of people, not just in Wales but across the UK and beyond - so I'm delighted this vital strategic investment will enable us to plan for our future with real confidence."
First Minister Carwyn Jones said: "Today's announcement is a significant milestone for BBC Wales and for Wales' creative industries which are flourishing and have become talked about worldwide."
Cardiff council leader Phil Bale said the development created a "capital that everyone can be proud of".