Hunniford starts as a BBC production assistant in Belfast and a local radio broadcaster. In the 1970s and 1980s, she is the presenter of Good Evening Ulster and on the ITV Network Sunday Sunday and We Love TV. She also appears on Lily Savage’s Blankety Blank and on Call My Bluff. She is a regular reporter on This Morning and The One Show.
From 1998 to 2003, Hunniford presents Open House with Gloria Hunniford for Channel 5. In August 2010, she appears as a panellist/presenter on the ITV daytime programme 3@Three. Since 2009, she has co-presented Rip Off Britain, a consumer complaints programme on BBC One with Angela Rippon and, for the first two series, Jennie Bond, and then, for the third series, with Julia Somerville replacing Bond. Together, the trio of Hunniford, Rippon and Somerville also present Charlie’s Consumer Angels.
In 2012, Hunniford presents the BBC One documentary series Doorstep Crime 999. From September 8, 2014, she is a presenter on ITV chat show Loose Women. She is previously a guest panelist in 2003. From September 2014 to July 2015, she appears on the panel in 31 episodes of the programme, three of which she anchors. As of April 6, 2017, she has appeared 93 times, four of which she anchors and two where she is a guest panelist.
In 2014, Hunniford presents the first series of the BBC One programme Home Away from Home. Gyles Brandreth presents the second series. She also presents three series of Food: Truth or Scare with Chris Bavin from 2016.
Hunniford makes a health and exercise video called Fit for Life and also appears on the UK music video of the Muppets cover to “She Drives me Crazy.” She has written an Irish Cookery Book with her sister Lena entitled Gloria Hunniford’s Family Cookbook.
On The Alan Titchmarsh Show on May 6, 2011, Hunniford reveals her support for David Cameron‘s Conservative-led coalition government, describing herself as “a bit of a David Cameron fan,” although she criticises the government’s decision to continue giving aid to Pakistan when it is making cuts in the UK.
In August 2014, Hunniford is one of 200 public figures who are signatories to a letter to The Guardian opposing Scottish independence in the run-up to September’s referendum on that issue.
Together with Kevin Gildea and Barry Murphy, O’Hanlon founds the International Comedy Cellar, upstairs in the International Bar on Dublin’s South Wicklow Street. Dublin has no comedy scene at the time. As a stand up, he wins the Hackney Empire New Act of the Year competition in 1994. For a time, he is the presenter of The Stand Up Show.
O’Hanlon moves into straight acting alongside Emma Fielding and Beth Goddard in the ITV comedy-drama Big Bad World, which airs for two series in summer 1999 and winter 2001. He also plays a minor role in The Butcher Boy and appears in an episode of the original Whose Line is it Anyway?.
In 2000, O’Hanlon stars in the comedy series My Hero, in which he plays a very naive superhero from the planet Ultron. His character juggles world-saving heroics with life in suburbia. He stays in the role until the first episode of series 6 in July 2006 where he is replaced by James Dreyfus during the same episode.
O’Hanlon also provides the voice of the lead character in the three Christmas television cartoon specials of Robbie the Reindeer. He appears in the 2005 BBC One sitcom Blessed, written by Ben Elton. Towards the end of 2005, he plays an eccentric Scottish character, Coconut Tam, in the family-based film, The Adventures of Greyfriars Bobby. Although more commonly on television, he also appears on radio. In 2015 he appears as incompetent angel Smallbone in the sitcom The Best Laid Plans, also on BBC Radio 4.
In 2006, O’Hanlon writes and presents an RTÉ television series called Leagues Apart, which sees him investigate the biggest and most passionate football rivalries in a number of European countries. He follows this with another RTÉ show, So You Want To Be Taoiseach? in 2007. It is a political series where he gives tongue-in-cheek advice on how to go about becoming Taoiseach of Ireland.
O’Hanlon appears in the Doctor Who episode “Gridlock“, broadcast on April 14, 2007, in which he plays a cat-like creature named Thomas Kincade Brannigan. He appears in Series 3 of the TV show Skins, playing Naomi Campbell’s Politics teacher named Kieran. He then goes on to form a relationship with Naomi’s mother, played by Olivia Colman. He plays the lead role in Irish comedy television programme Val Falvey, TD on RTÉ One.
O’Hanlon has written a novel, The Talk of the Town, which is published in 1998. The novel is about a teenage boy, Patrick Scully, and his friends.
In February 2015 O’Hanlon officially launches the 2015 Sky Cat Laughs Comedy Festival which takes place in Kilkenny from May 28–June 1. In 2015 he plays the role of Peter the Milkman in the Sky One sitcom After Hours.
On February 2, 2017, it is announced O’Hanlon will play the lead role in the BBC crime drama Death in Paradise taking the role of DI Jack Mooney following Kris Marshall‘s departure the same day.