[8] He grew up in Kidderminster[9] after being adopted at the age of 28 days by Jim O'Brien, a journalist on the Doncaster Evening News[10] (who later joined The Daily Telegraph) and his wife.

[citation needed] Prior to his broadcasting career, O'Brien was an editor of the Daily Express gossip column, written under the pseudonym William Hickey.

[21][22][23] Following the widespread interest in O'Brien's interview with Farage, it was speculated he would be a permanent replacement for longtime host Jeremy Paxman, who intended to step down.

[25] O'Brien left Newsnight in January 2018 after being criticised for his anti-Brexit and anti-Trump views, which were felt to be out of step with the corporation's policy on neutrality.

[6] Regular features of his show include the "Mystery Hour," in which listeners phone in with various things that puzzle them and other callers attempt to give a solution.

During the interview, O'Brien picked up on Farage's comment that he felt uncomfortable on a train at not being able to hear anyone speaking English.

[32] Throughout 2014 and 2015, O'Brien gave much air time and promotion to false claims of VIP sex abuse by the now discredited Exaro News website, which were based on testimony from Carl Beech, later sentenced to prison for perverting the course of justice and child sex offences,[33][34] something O'Brien later expressed regret for on Twitter.

[35] In August 2024, O'Brien apologized for praising a social media video that attributed some of the violence during the 2024 United Kingdom riots to "Zionist backers" during an LBC broadcast.

Guests included Russell Brand, Alastair Campbell, Lily Allen, Jon Ronson, Gary Lineker and Sir Nick Clegg.

[41] Other notable guests have included David Mitchell, Nicky Campbell, Margaret Atwood, Michael Morpurgo, Keir Starmer recorded at Leicester Square Theatre.

[51] In 2023, O’Brien was ranked number thirty-eight in the New Statesman’s Left Power List 2023, with the publication describing him as a “liberal firebrand” and “master of the sound-bite”.