Possessing an early ambition to become a professional tennis player, she spent two years at a tennis academy in Florida. Richardson then turned to acting. In 1985 she portrayed, via flashbacks, the younger version of the leading character played by her mother in the film Wetherby. After a leading role in Peter Greenaway's cult success Drowning by Numbers (1988), her first major role in front of a mass audience was as Joanna Farley in a 1989 television episode of Poirot, the Agatha Christie based detective series. In a 1989 episode of Jim Henson's The Storyteller she was cast as a princess. She portrayed a teacher on the verge of a nervous breakdown in the 1989 Channel 4 serial Behaving Badly and fictional Finnish Princess Anna in the 1991 screen comedy King Ralph.
A year later, she appeared in Shining Through alongside her future brother in law Liam Neeson, where both played characters who were Nazis.
In 1993, Richardson appeared as Lady Chatterley opposite Sean Bean in a television drama of the same title. In 1996, she played fashion designer Anita Campbell-Green in the Disney live-action remake of the animated 101 Dalmatians opposite Glenn Close as Cruella de Vil. In 1998, in the popular television drama The Echo, she played sultry Amanda Powell. The next year, she played in the science fiction/horror movie Event Horizon as Lieutenant Starck, executive officer of the research and rescue ship Lewis and Clark, sent to rescue crew of the long thought lost experimental ship Event Horizon.
One year later, Richardson played opposite Mel Gibson in the film The Patriot, an American film based on the American Revolution. Later that year, she was modelling a necklace, when director Charles Shyer noticed her resemblance to doomed 18th century French Queen Marie Antoinette. Thus, she secured the role of that queen in the 2001 film The Affair of the Necklace. Also in 2000, she played opposite Hugh Laurie in Maybe Baby, Ben Elton's movie adaptation of his book Inconceivable.
In 2003, Richardson took on the role of Julia McNamara in the television drama Nip/Tuck, based on the lives of two dysfunctional plastic surgeons in Miami. Her mother, Vanessa Redgrave, has appeared in several episodes, playing her character's mother. In November 2006, it was announced that Richardson would be leaving Nip/Tuck to take care of her sick daughter. Her last appearance was on the 14 November episode, although creator/writer Ryan Murphy wrote alternate season finale episodes, in case Richardson decided to return. Soon after the season finale, it was announced that Richardson would return for the fifth season of Nip/Tuck, though her role may be limited. In June 2007 it was announced that she would return for fifteen of the twenty two episodes during the fifth season.
In 2005, Richardson starred in Lies My Mother Told Me, based on a true story about a murderous con artist. In 2007, she played the mother in The Last Mimzy with Timothy Hutton and Chris O'Neil. She also starred in the television drama Wallis & Edward, playing the lead role of Wallis Simpson, lover of Edward, Prince of Wales.
Richardson is signed to Models 1.
On 23 July 2009 it was announced that Richardson had been cast as Queen Catherine Parr in the fourth and final series of Showtime's hit period drama The Tudors. The role would reunite her with her ex husband Tim Bevan, who is part of the show's production team. It was further reported that Gillian Anderson had been vying for the part. Other actresses linked with the role include Keira Knightley and Kate Winslet.
|1968||The Charge of the Light Brigade||extra|
|1985||Wetherby||Young Jean Travers|
|1988||Drowning by Numbers||Cissie Colpitts 3|
|1989||A proposito di quella strana ragazza||Giovanna Serafin (Maria)|
|1991||King Ralph||Princess Anna|
|Shining Through||Margrete Von Eberstein|
|1993||Lady Chatterley||Lady Chatterley|
|1994||Sister My Sister||Christine|
|I'll Do Anything||Cathy Breslow|
|1996||Loch Ness||Laura McFetridge|
|1997||Event Horizon||Lt. Starck|
|1998||Wrestling with Alligators||Claire|
|2000||Maybe Baby||Lucy Bell|
|Return to Me||Elizabeth Rueland|
|The Patriot||Charlotte Selton|
|2001||The Affair of the Necklace||Marie-Antoinette|
|2004||The Fever||Woman at 30|
|2005||Lies My Mother Told Me||Laren Sims|
|Wallis & Edward||Wallis Simpson|
|2006||Fatal Contact: Bird Flu in America||Dr. Iris Varnack|
|2007||The Last Mimsy||Jo Wilder|
|The Christmas Miracle of Jonathan Toomey||Susan McDowel|
|2009||The Day of the Triffids||Jo Playton|
|Agatha Christie's Poirot - Murder on the Orient Express||Mary Debenham|
|2010||The Tudors||Catherine Parr|
|2011||Anonymous||Princess Elizabeth Tudor|
|The Girl with the Dragon Tattoo||Anita Vanger|