Daly was born in Derbyshire to Vivian (1932-2003), who died of emphysema, and Sylvia Daly and grew up in Birch Vale near New Mills, Derbyshire. She attended Hayfield Primary School and New Mills Secondary School. She has a younger sister, Karen.
In 1990, Daly appeared in two Duran Duran videos for the songs "Serious" and "Violence of Summer (Love's Taking Over)", both from the album Liberty. She also appeared in the video for The Beloved's 1993 song "Sweet Harmony".
After working as a model, her first television appearance was in 2000, when she hosted the Find Me a Model competition on Channel 4's The Big Breakfast. Since then, she has presented shows including Get Your Kit Off, Singled Out, Smash Hits TV, SMTV Live, Back To Reality, the first series of Make Me a Supermodel (with Dave Berry) and Strictly Come Dancing, which she has co-hosted with Bruce Forsyth in all ten series to date. Daly missed a couple of episodes in the second series because she was pregnant with her first daughter. Natasha Kaplinsky, the first series winner, took her place.
Recently, Daly has also hosted This Time Tomorrow, the National Lottery show broadcast on BBC1. On 14 November 2008, she presented Children in Need with Terry Wogan and Fearne Cotton. Daly won the special version of Strictly Come Dancing against Wogan, where she was partnered with Anton du Beke. She co-hosted the Royal Variety Performance 2008 on 11 December, broadcast on 17 December 2008.
She was the face of lingerie company La Senza in the UK and appeared in their Steal the Show Christmas 2009 campaign.
Her first novel, The Camera Never Lies, a tale of love behind the scenes, was published by Coronet, an imprint of Hodder & Stoughton in 2011. It's Up to You New York, Daly's second book will be released in 2013.
Daly married Vernon Kay on 12 September 2003, at St Mary's Catholic Church in Horwich, Bolton. The couple have two children, Phoebe Elizabeth Kay, who was born in Westminster, London, on 17 October 2004, and Amber Isabella Kay, born on 30 May 2009, also in London. In January 2007, Kay and Daly co-presented the second series of Just the Two of Us on BBC One. They live in Fulmer, Buckinghamshir