She was a member of Laurence Olivier's National Theatre Company at the Old Vic from 1971–73 and of the Royal Shakespeare Company for its 1973 Stratford season. She made an early film appearance in Up the Junction (1968).

Lipman is Jewish. She was married to dramatist Jack Rosenthal from 1974 until his death in 2004, and has had a number of roles in his works. She has two children, Writers Amy and Adam Rosenthal. Lipman was a Labour Party supporter, but in October 2014 declared that she will no longer be voting Labour due to the party's support for recognition of Palestine. She is on the editorial advisory board of Jewish Renaissance magazine.

After early appearances in the sitcoms The Lovers, and Doctor at Large, and a role in The Evacuees (1975), Lipman first gained prominence on television in the 1979 situation comedy Agony, in which she played an agony aunt with a troubled private life.

After her Playwright husband's death in May 2004 she completed his autobiography By Jack Rosenthal, and played herself in her daughter's four-part adaptation of the book, Jack Rosenthal's Last Act on BBC Radio Four in July 2006. She has created several volumes of autobiography from her Good Housekeeping columns and recently published The Gibbon's In Decline But The Horse Is Stable, a book of animal poems which is illustrated by established cartoonists including Posy Simmonds and Gerald Scarfe, to raise money for Myeloma UK, to combat the cancer to which she lost her husband.

Lipman supported Israel during the 2006 Israel-Hezbollah conflict. On 13 July 2006, in a debate on the BBC's This Week, she argued that "human life is not cheap to the Israelis, and human life on the other side is quite cheap actually, because they strap bombs to people and send them to blow themselves up." These comments were condemned by columnist Yasmin Alibhai-Brown who said "Brutally straight, she sees no equivalence between the lives of the two tribes". Lipman responded to Alibhai-Brown's accusation of racism by arguing that the columnist had deliberately misrepresented Lipman's comments as generalisations about Muslims rather than specific comments about terrorists.

She has also appeared a few times on Just a Minute, The News Quiz, That Reminds Me, This Week and Have I Got News for You. In 2007, Lipman appeared as a Celebrity contestant on Comic Relief Does The Apprentice to raise money for Comic Relief. The show saw her helping to run a funfair. Later in 2007, she made a guest appearance in Casualty; this was followed by an appearance in a December 2011 episode of the Casualty-spin off Holby City, playing a different character.

Lipman supports the work of the Burma Campaign UK, Europe's largest NGO regarding Burma. Lipman supports the process of democratisation in the country. Lipman also supports the work of Prospect Burma, a non-political charity that offers Burmese students the opportunity to study at universities outside of Burma. Lipman spoke on behalf of Prospect Burma in the BBC Radio 4 Charity Appeal, which was broadcast on 6 September 2009.

From October 2010 to February 2011, Lipman starred in a production of J B Priestley's When We Are Married at the Garrick Theatre. In 2012 she directed and appeared in a production of Barefoot in the Park on tour and starred in Old Money at the Hampstead Theatre. In 2013 she starred in Daytona at The Park Theatre followed by a tour, and in 2014 a season at the Theatre Royal Haymarket. In 2015 she starred with James Dreyfus in Mary Chase's play Harvey at Birmingham Rep, on tour and at the Theatre Royal Haymarket. In 2016 she starred in My Mother Said I Never Should at the St. James Theatre. In 2017 she starred with Felicity Kendal in a revival of Lettice and Lovage at the Menier Chocolate Factory. In 2018 she starred with Martin Shaw in The Best Man at the Playhouse Theatre.

Lipman worked extensively in the theatre following her début in a stage production of The Knack at the Palace Theatre, Watford. In order to get the post she pretended that a documentary Producer wanted to follow her finding her first job – this was a lie but it seemed to work.

In May 2015, Maureen Lipman joined pro-Israel groups including Zionist Federation in a protest outside the London premiere of a Palestinian play, The Siege, at Battersea Arts Centre.

In April 2018, Lipman criticised Labour Party leader Jeremy Corbyn for his party’s alleged failure to address anti-Semitic prejudice within the party. Lipman said she attended the protest “as a disenfranchised socialist”. She identified with a placard reading “Corbyn made me a Tory”. She had also previously criticised then leader of the Labour Party, Ed Miliband, in 2014, when she announced she was no longer a supporter of the Party due to Miliband's support for a parliamentary motion in favour of recognising the State of Palestine.