Twice in the 1960s Bellingham appeared in the Pendley Open Air Shakespeare Festival. She got her big break as a nurse in an ITV afternoon soap opera of the 1970s, General Hospital. She went topless for her roles in Confessions of a Driving Instructor and Sweeney! (1977).
She is best known as the head of the family in the Oxo television adverts during the 1980s. Other prominent roles included the James Herriot drama All Creatures Great and Small (where she was the second actress to play Helen Herriot on television, replacing Carol Drinkwater) and the situation comedy Second Thoughts and its sequel, Faith in the Future.
She starred in the 14-part Doctor Who serial The Trial of a Time Lord (1986) as the Inquisitor. Bellingham reprised the Inquisitor character for the Big Finish Productions audio series, Gallifrey. In 1998 she appeared in Gleb Panfilov's The Romanovs: A Crowned Family as Empress Alexandra.
From 2000 to 2003, Bellingham played Pauline Farnell, the compassionate accountant in At Home with the Braithwaites alongside Amanda Redman and former All Creatures Great and Small colleague Peter Davison. For several months in 2004, she had a recurring role in The Bill as villainess Irene Radford.
She also had a memorable role in the ITV comedy Bonkers playing Mrs Wadlow, a man-eating suburban housewife who seduces her neighbour's teenage son and turns him into her gigolo. Later that year she filmed guest appearances in episodes of Love Soup and Robin Hood.
In October 2007, she appeared in a play entitled Vincent River at the Trafalgar Studios in London. Her performance received critical acclaim, and it was announced on Loose Women in early 2008 that the play would be moving toBroadway in July of that year, although this never actually transpired.
From September 2008 to July 2009 she played the role of Chris Harper in the stage version of the hit film Calendar Girls on tour and at the Noel Coward Theatre in the West End. She returned to the show for further tours in 2010, 2011 and 2012.
Over the Christmas/New Year period of 2011/12 she played Fairy Godmother in the pantomime Cinderella at the Birmingham Hippodrome. She played the role again at the Alhambra Theatre, Bradford over the Christmas/New Year period of 2012/13.
Since 2007, she has been doing the voice-over on the Vodafone adverts with the slogan: Make the most of now.
In 2009 she was one of the contestants in the seventh series of Strictly Come Dancing, the BBC ratings winner where she partnered Darren Bennett. However, she was voted out by the judges in the fourth week.
Since 2011, she has been the face of online shopping brand isme.com
In 2010, Bellingham launched her book Lost and Found, a story of her life and career and toured the country for private readings.
- General Hospital (1970s)
- Confessions of a Driving Instructor (1977)
- Sweeney! (1997)
- Doctor Who: The Trial of a Time Lord (1986)
- This Is Your Life (1993)
- The Romanovs: An Imperial Family (1998)
- At Home with the Braithwaites (2000-2003)
- The Bill (2004)
- Bonkers! (2007)
- Loose Women (2007-2011)
- My Tasty Travels with Lynda Bellingham (2012)
- Country House Sunday (2013—)
Bellingham has been married three times, first in 1975 to film and theatre producer Greg Smith, best remembered for the Confessions films. Her second marriage (1981–1996) was to Nunzio Peluso with whom she had two sons, Michael and Robbie.
On 31 May 2008, she married her boyfriend, Spanish-based mortgage broker Michael Pattemore (known on Loose Women as "Mr Spain") at St Stephen Walbrook on her 60th birthday. On 3 March 2010, whilst being interviewed on This Morning, Lynda announced she would be returning to do more Oxo commercials.