Dent is well known as the resident lexicographer and adjudicator on Channel 4's long-running game show Countdown. She is the show's longest-serving member of the on-screen team, having first appeared in 1992and has made over a thousand appearances. Alison Heard replaced Susie Dent as lexicographer over the winter of 2007–08, while she was on maternity leave which ended on 6 February 2008.
From 2003 to 2007 she was the author of a series of annual Language Reports for the OUP. The first was entitled simply The Language Report; it was followed by Larpers and Shroomers (2004), Fanboys and Overdogs (2005), The Like, Language Report for Real (2006) and The Language Report: English on the Move 2000 – 2007 (2007). The format of this publication was revised for 2008 as an A–Z collection of new and newly resurrected words. It was published in October 2008 as Words of the Year. In 2005 the same publisher issued Winning Ways (ISBN 0199198748). 2009 OUP published her latest work: What Made the Crocodile Cry? 101 questions about the English language (ISBN 0199574154). Dent's book about dialects, How to Talk Like a Local (ISBN 1905211791), was published in March 2010.