Hill was educated at Monkwearmouth School before attending the Royal Academy of Dramatic Art in London, where she won the Vanbrugh award.
Hill replaced Gilly Coman as the character of Aveline in the last three series' of Carla Lane's BBC television sitcom Bread. She has also appeared in such programmes as The Bill playing Marie Carver (née Graham), Auf Wiedersehen, Pet playing Hazel Redfern, Hot Money playing Liz Hoodless, Juliet Bravo playing Jean Simpson, Emmerdale playing Avril Kent and Cape Wrath playing Brenda Ogilvie.
On 17 March 2009, she featured in an episode of Holby City, a medical drama broadcast weekly on BBC1 in the United Kingdom. This became a recurring role, as the actress appeared in subsequent episodes, following a story arc relating to the death of her on-screen husband. She also appeared in an episode of The Thick of It (series 3 episode 3).
In April 2011, she appeared in the BBC television comedy drama series Candy Cabs and in November, appeared in the fantasy series Merlin as Mary Howden. In April that year, she also appeared as Cissie Charlton, mother of footballers Jack and Bobby Charlton, in the BBC drama United, which was centred on the 1958 Munich air disaster involving Manchester United and in which Cissie's younger son Bobby was involved but survived.
In 2012, she made her debut on long-running school drama Waterloo Road her character, Maggie Croft (now Budgen), is head of the canteen and house mistress of the building that is a home to many pupils and also got married to Grantly Budgen (Philip Martin Brown), making her Grantly's new wife. Also in 2012 she was in Coronation Street.
In August 2013, it was announced that Hill has joined the cast of the BBC Two sitcom Hebburn.
In February 2015, it was announced that Hill would join the cast of Coronation Street as Cathy Matthews. She made her first appearance as Cathy on 20 April 2015. She was introduced as a potential love interest for Roy Cropper (David Neilson), which Hill was nervous about as Roy's deceased wife, Hayley (Julie Hesmondhalgh), was loved by the nation. Most recently (June 2015) and currently, Hill is starring in the third series of The Syndicate and Playing the Field.
Hill appeared in Brassed Off (1996) as Sandra. She appeared as the witch Ditchwater Sal in the 2007 film Stardust and the 2008 film White Girl.
Born to Anthony Hill and Sylvia (née Pratt) in Brighton, Hill was raised in her mother's native city of Sunderland. She married English actor Sean Bean in December 1990. The couple have two daughters, Lorna, born October 1987, and Molly, born September 1991. They divorced in August 1997. She is a supporter of Sunderland A.F.C. She married writer and producer Jimmy Daly on 29 April 2017 at a pub in Muswell Hill, North London.