Riding was born in Lancashire, England, growing up on a farm, where her father ran a successful cheese-making business. She received theatre training at the Bristol Old Vic Theatre School from 1986–1989.
After leaving school, Riding worked at Chichester Festival Theatre for a season, playing Anne Page in The Merry Wives of Windsor and Dorothy in The Wizard of Oz. She met her former husband, actor Peter O'Brien, at Chichester. She was next cast as a replacement Sally in the West End production of Me and My Girl.
In 1993, Riding played the role of Julie Jordan in Nicholas Hytner's Royal National Theatre revival of Carousel and won the Olivier Award for Best Actress in a Musical for her performance. Also in 1993, she appeared as Sean Hughes' love interest 'Lizzie Workman' in the second series of Sean's Show. Her character was introduced via a parody of Grease's 'Summer Nights'.
In 1995 she played Anne Egerman in A Little Night Music opposite Judi Dench, followed by Sarah Brown in Richard Eyre's acclaimed revival of Guys and Dolls, both at the National Theatre. She created the role of Jane Smart in The Witches of Eastwick in 2000, at the Theatre Royal, Drury Lane and in 2002 played the role of Eliza Doolittle in Trevor Nunn's National Theatre revival of My Fair Lady, for which she won her second Olivier Award.
On 12 May 2002, she appeared in the Richard Rodgers' Tribute Gala 'Some Enchanted Evening' at the Theatre Royal, Drury Lane, which was broadcast on BBC Four and has since been released on DVD. At the concert she performed the song "An Old Man" from Two by Two.
From 1 December 2008 to 29 May 2010, Riding starred as Mrs. Wilkinson in the London production of Billy Elliot the Musical at the Victoria Palace Theatre. She took maternity leave from the show between 23 December 2008 and 24 August 2009 when the role was played by Kate Graham. Following this, she headlined a one-off late afternoon concert on 24 October 2010 at Freedom Bar in Soho called Sondheim in Reverse, as part of the composer's 80th birthday celebrations.
In 2011, Riding starred in two musicals at the Gielgud Theatre in London's West End. From 5 March to 21 May, she played Madame Emery in the Kneehigh Theatre Company's musical adaptation of The Umbrellas of Cherbourg. The production had its try-out at Leicester's Curve Theatre from 11 to 26 February. A month later, from 6 June to 6 August, she played jealous Italian mistress Maria Merelli in the London production of Lend Me A Tenor.
In 2013 she appeared in the Sky1 TV comedy series Stella as Melissa. Riding also portrayed Valerie Hobson in Andrew Lloyd Webber's musical Stephen Ward, and was one of few elements of the production to be praised by every major critic.
In September 2016 it was announced that Riding would take the leading role of Annie in The Girls musical written by Gary Barlow and Tim Firth to open at The Phoenix Theatre, London on 27 January 2017.
|1993||Laurence Olivier Award||Best Actress in a Musical||Carousel||Won|
|1997||Laurence Olivier Award||Best Actress in a Musical||Guys and Dolls||Nominated|
|2001||Laurence Olivier Award||Best Actress in a Musical||The Witches of Eastwick||Nominated|
|2003||Laurence Olivier Award||Best Actress in a Musical||My Fair Lady||Won|
|2017||Laurence Olivier Award||Best Actress in a Musical||The Girls||Nominated|