William Crawley was born and raised in north Belfast. Crawley was educated at Grove Primary School, Dunlambert Secondary School, Belfast Royal Academy and Queen's University, where he read philosophy (B.A., M.Phil.). He read theology (M.Div.) at Princeton Theological Seminary. He earned a doctorate in philosophy (Ph.D.) for a dissertation on the epistemology of the American philosopher Alvin Plantinga from Queen's University.
Prior to his career in the media, he worked as a university lecturer in philosophy and theology and, having been licensed, then subsequently ordained into the ministry of the Presbyterian Church in Ireland in the mid-1990s, worked as assistant minister in First Presbyterian Church, New York City, and Fisherwick Presbyterian Church, Belfast, before serving as Presbyterian chaplain at the University of Ulster. He later resigned from the ordained ministry and from membership of the church before beginning his career as a journalist. He has described himself as "a lapsed Protestant."
Blueprint NI, a three-part series examining Ireland's natural history, first broadcast in 2008.
The late-night television interview show, William Crawley Meets..., a series of 30 minutes in duration with leading thinkers and social reformers from across the world, including the philosopher Peter Singer, the scientist Richard Dawkins, the writer and broadcaster Melvyn Bragg, and the gay bishop Gene Robinson.
Frozen North (BBC One, 2008), a documentary examining the possible future impact of global warming.
Festival Nights (BBC Two), television coverage of the 2005, 2006 and 2007 Belfast Festival at Queens.
Hearts and Minds, a Northern Ireland politics programme.
What's Wrong With ...? (BBC One), a six-part round-table current affairs discussion programme.
More Than Meets The Eye (BBC Two, 2008), a series investigating folklore in contemporary Ireland.
He anchored the BBC's live coverage of the Queen's official visit to Northern Ireland in 2008.
In 2010, he presented an episode of Spotlight (BBC One NI) concerning the Vatican.
In 2012, he wrote and presented a 60-minute documentary exploring the history of the Ulster Covenant.
In 2013, his series An Independent People examined the history of Ireland's Presbyterians.
His 2013 one-hour documentary It's a Blas followed his year-long effort to learn Irish sufficiently-well to present a live radio programme in the language.
The 2013 programme The Man Who Shrank The World told the story of the engineering feat carried out by the scientist Lord Kelvin in the creation of a transatlantic communications cable was made as part of the Groundbreakers series for BBC Four.
His 2014 four-part series for BBC Two Northern Ireland, It's a Brave New World -- New Zealand, examined the links between Northern Ireland and New Zealand.