Mackichan had her television debut in comedy series
Five Alive, shown by
Channel 4 between 1987 and 1988, along with
Brian Conley (also making his television debut), Peter Piper, Joanna Brookes and
Andrew Secombe. In series 2, shown in 1988, Andrew Secombe was replaced by
Phil Nice. Mackichan, one of the writers and stars of the
Channel 4 comedy series
Smack the Pony, has appeared in a number of
Chris Morris radio and television comedy series such as
On the Hour,
The Day Today and
Brass Eye. Mackichan's own BBC Radio show,
Doon Your Way, was broadcast in 1996. She also appeared in the sitcoms
Beast and
Bedtime, and was a regular performer in
Knowing Me, Knowing You... with Alan Partridge and
The Mary Whitehouse Experience. She appeared in several of
The Comic Strip Presents... films in the early 1990s, and appeared in the 1995 comedy
The Glam Metal Detectives. In 2009, she appeared as Jane Thomason, the news producer for the BBC in
Taking the Flak. She portrayed
Cherie Blair in the Channel 4 satirical drama
A Very Social Secretary, and appeared in the Channel 4 sitcom
Nathan Barley. She portrayed a BBC news presenter, Louise Marlowe, in series 4 of
The Sarah Jane Adventures in 2010. In film, Mackichan played Victoria Lender in 1997's
The Borrowers and teamed up with her former
Smack the Pony co-stars for the 2004 film
Gladiatress. Also in 1998 she appeared in the BBC TV mini-series of Dickens' novel
Our Mutual Friend as Sophronia Lammle. On stage, she appeared with
Matt Di Angelo and
David Haig in the
Joe Orton black farce
Loot. In July 2011, Mackichan performed alongside
Julian Barratt in
Nikolai Gogol's comedy
The Government Inspector at the
Young Vic Theatre, London. Later in 2011, she played the part of Frances in April de Angelis' play
Jumpy at the
Royal Court Theatre. Since 2013, Mackichan has starred in
Toast of London as Steven Toast's (
Matt Berry) quirky agent Jane Plough. She has narrated several TV series including
The Honey Trap and
Bank of Mum and Dad. She has also voiced characters in several animated series including
Bob and Margaret,
Stressed Eric, ''
Don't Eat the Neighbours and Bromwell High''. She fronted a TV ad campaign for
Hallmark in the UK, and appeared alongside
Darren Boyd as one half of a married couple for a series of
Direct Line insurance TV ads in 2012. She was a contestant in the 2003
BBC charity singing contest
Comic Relief does Fame Academy, in which she came fourth. She has appeared twice on the BBC panel show
QI, in series C, episode 2, ("Cummingtonite", 2005) and series E episode 11, ("Endings", 2007). From 2013 until 2018, Mackichan played Flavia, a recurring character, in the
ITV comedy
Plebs, for which she was nominated for the
British Academy Television Award for Best Female Comedy Performance in 2014. She played Cathy in the BBC comedy
Two Doors Down from 2013 until 2022, when she decided to quit the show to concentrate on other acting roles. In June 2023 it was announced she would be returning to this role in the forthcoming series. In 2017 she played
Feste in the
Royal National Theatre's production of
Twelfth Night and television film
Death on the Tyne in 2018. Mackichan appeared as the Archangel Michael in the
Amazon Prime/
BBC mini-series
Good Omens and as Sarah in
Channel 4 comedy-drama
Pure in 2019. In 2019 she appeared as Sondra in
David Mamet's
Bitter Wheat at the
Garrick Theatre. Writing in
The Guardian,
Michael Billington praised her as having given the show's best performance. Mackichan was cast as the Archangel Michael in seasons 2 and 3 of the series
Good Omens. In 2024, Mackichan won the
Bafta Award for Best Actress Television for her work in
Two Doors Down. ==Personal life==