McCutcheon appeared in ITV's The Knock as well as the British film Kiss Kiss (Bang Bang) in 2000. She went on to play Eliza Doolittle in My Fair Lady in London's West End. Despite being plagued by health problems during her run, she won the award for best actress in a musical at the 2002 Laurence Olivier Awards. In 2002, McCutcheon presented the National music awards for ITV1 and in 2003 she featured in her first major film role. She appeared as tea-lady Natalie in the Richard Curtis romantic comedy Love Actually, where the British Prime Minister (played by Hugh Grant) falls in love with McCutcheon's character. The film received good reviews and was a box office success. McCutcheon went to America in the wake of the film's success, but a Hollywood career did not materialize. She did however, win Best Trans-atlantic breakthrough at the 2004 MTV Movie Awards.

In September 2005 she appeared in two episodes of hit BBC drama series Spooks, playing a waitress who witnesses a terrorist bombing. Screened on the UK television station ITV1 in December 2005, McCutcheon appeared in The English Harem, playing a woman in love with a Muslim man (Art Malik), who marries him despite knowing he already has two wives. That same year she presented and performed on ITV's entertainment programme, Moviemusic Mania.

In 2007, McCutcheon was seen in two independent films, Withdrawal opposite Patrick Swayze and Jump!, as well Marple episode At Bertram's Hotel, where she plays a maid named Jane Cooper that assists Miss Marple with her investigations. She was also a judge in the second series of ITV1's Soapstar Superstar. Her appearance on the show drew criticism, with reports alleging that she was becoming a hate figure for the contestants, who were said to have found her comments relentlessly critical and at times patronising. McCutcheon performed in an Art Plus fundraising event at the Whitechapel Art Gallery opposite Natalie Press, Samantha Morton and Rhys Ifans and in January 2008 she starred alongside actor Jason Donovan, in the new ITV show Echo Beach.

• "Echo Beach" .... Susan Penwarden (12 episodes, 2008)
       - Episode #1.12 (2008) TV episode .... Susan Penwarden
       - Episode #1.11 (2008) TV episode .... Susan Penwarden
       - Episode #1.10 (2008) TV episode .... Susan Penwarden
       - Episode #1.9 (2008) TV episode .... Susan Penwarden
       - Episode #1.8 (2008) TV episode .... Susan Penwarden
        (7 more)
• Marple: At Bertram's Hotel (2007) (TV) .... Jane Cooper
  ... aka Miss Marple: At Bertram's Hotel (USA: new title)
• Jump! (2007/I) .... Liuba Halsman
• Withdrawal (2006) .... Bonnie
• The English Harem (2005) (TV) .... Tracy Pringle
• "Spooks" .... Tash (2 episodes, 2005)
  ... aka MI-5 (USA)
       - The Special: Part II (2005) TV episode .... Tash
       - The Special: Part I (2005) TV episode .... Tash
• Love Actually (2003) .... Natalie
• "The Knock" .... Jenny Foster (1 episode, 2000)
       - Episode #5.2 (2000) TV episode .... Jenny Foster
• Kiss Kiss (Bang Bang) (2000) .... Mia
  
• "EastEnders" .... Tiffany (338 episodes, 1995-1998)
       - Episode dated 31 December 1998 (1998) TV episode .... Tiffany
       - Episode dated 28 December 1998 (1998) TV episode .... Tiffany
       - Episode dated 25 December 1998 (1998) TV episode .... Tiffany
       - Episode dated 24 December 1998 (1998) TV episode .... Tiffany
       - Episode dated 21 December 1998 (1998) TV episode .... Tiffany
        (333 more)
• "The Bill" .... Amanda Jones / ... (2 episodes, 1991-1992)
       - A Scandalous Act (1992) TV episode .... Amanda Jones
       - Skeletons (1991) TV episode .... Paper Girl