2006–2015: Early career and theatre In the first ten years of her professional acting career, Clifford became a prolific
Off West End actress. In her first few years out of drama school, she was involved with
Theatre503 in which she was involved the productions
Without Laughing,
Contraction, and
Listening Out. In March 2007, she acted in the play
Not the End of the World at the
Bristol Old Vic theatre. Her first notable performance was playing Ismene in the Nottingham Playhouse production of
Burial at Thebes at
the Barbican which premiered in September 2007. In Summer 2008, she acted in a play called
The Pendulum, written by her co-star
Alexander Fiske-Harrison, at the Jermyn Street Theatre in the
West End, which ran for the month of June, and in the following month she took part in the annual
Latitude Festival in the play
Public Displays of Affection. Clifford was in three theatre productions the next summer; in June she had a small role in a
chamber opera titled
Parthenogenesis at the
Royal Opera House's Linbury Studio, she co-starred in the
Arcola Theatre play
The Road to Mecca, and she toured with the production
Is Everyone Okay? which co-starred future
Fleabag castmate Phoebe Waller-Bridge. Throughout September 2010, Clifford starred in the well-reviewed experimental theatre piece
Pieces of Vincent at the Arcola Theatre. For the rest of autumn 2010, she had a supporting role in the play
Pains of Youth at the prestigious
Royal National Theatre. Finishing out the year, Clifford held the titular role in an original production of
Beauty and the Beast, also at the Royal National Theatre. The production ran throughout the Christmas season and was critically successful. In 2014, she was one of the stars of the
Nottingham Playhouse's production of
Time and the Conways. Also that year, she took part in
Good. Clean. Fun., a collection of short plays by Phoebe Waller-Bridge which included an early version of Clifford's
Fleabag character Claire, as well as the Victorian-era play
Fever at the
Jermyn Street Theatre. During her career, Clifford has also participated in many workshops and readings for
Off West End productions. She has often collaborated with DryWrite and Nabokov theatre companies, theatre directors
Vicky Jones (DryWrite), Lyndsey Turner (
Royal National Theatre,
Theatre503) and Andrew Steggall, and writer/actor
Phoebe Waller-Bridge. In 2018, Clifford had a recurring role in the ITV miniseries
Vanity Fair and was in a production of
Circle Mirror Transformation in
Manchester. Later in 2018, Clifford was part of the cast in the West End production of
Consent at the
Harold Pinter Theatre.
Fleabag returned in 2019. Clifford's performance in the show was widely praised and she was nominated for the
Emmy Award for Supporting Actress in a Comedy Series and the
Critics' Choice Award for Supporting Actress in a Comedy Series for her performance. She later won the
BAFTA Television Award for Best Female Comedy Performance. In 2019, Clifford had a small role in the independent dark comedy film ''
A Serial Killer's Guide to Life. In 2020, Clifford had guest roles on the television shows Hitmen
on Sky One and Liar. She starred opposite Matthew Macfadyen in the April 2020 miniseries Quiz, based on the 2001 Charles Ingram Who Wants to Be A Millionaire? scandal. Clifford later co-starred in the Sky comedy series Two Weeks to Live''. In May 2021, Clifford starred as Iris in the
Inside No. 9 episode "Lip Service". In July 2021, Clifford voiced GS-8 in
Star Wars: The Bad Batch. In July 2024, Clifford starred as journalist Chloe Slack in
Time of the Week, a
BBC Radio 4 comedy series.{{cite web |title=Sian Clifford to star in Radio 4's Woman's Hour spoof In September 2025, it was announced Clifford had joined the cast of
BBC detective series
Ludwig, playing local MP, Joanne Kemper in the second series.{{Cite web |date=4 September 2025 |title=Ludwig series two begins filming as David Mitchell’s smash hit award-winning comedy detective series returns ==Personal life==