Television Kat Stewart is best known for her role as Roberta Williams (wife of the late Melbourne gangland figure
Carl Williams) in the first series of the Channel 9 TV production
Underbelly It was her award-winning performance in
Underbelly in 2008 that first made Stewart a household name. The portrayal of Roberta Williams drew praise from critics including Marcus Casey of
The Daily Telegraph, who described it as 'one of the most compelling performances by an Australian actress in memory.' Casey expanded that it was 'a brutally brave, ugly and compelling performance...She held nothing back, and was an emotional but controlled and screeching tornado who dominated the screen whenever the camera peered her way.' Although her performance was popular with critics and audiences, Stewart told David Knox of 'TV Tonight': "..Seven years ago when I did it we didn’t know much about Roberta Williams. So I did as much research as I could...Now we know how she walks and talks and so much more about her...I don’t like turning down work. It goes against every actor instinct. But it just didn’t feel right". In the series Stewart played the loveable but flawed, Nat Manning alongside
Justine Clarke,
Ben Mendelsohn,
Matt Day and
Catherine McClements. Showing she has long been adroit at both drama and comedy, in 2009 Stewart appeared in the Andrew Denton produced, advertising industry satire
:30 Seconds on Comedy Channel. Stewart won many new fans in her role as Billie Proudman on
Offspring, as part of an ensemble cast led by
Asher Keddie and including
John Waters,
Eddie Perfect,
Deborah Mailman,
Richard Davies,
Garry McDonald,
Lachy Hulme and
Linda Cropper. One of the show's strengths is the dynamic relationship between the sisters Billie and Nina Proudman (played by Keddie). Both actresses have spoken of their admiration for each other, with Stewart saying "I've admired Asher ever since
Love My Way. She is an actress of extraordinary ability and depth. We have a lovely shorthand and support for each other on set, not unlike Nina and Billie. There's a trust there that allows real spontaneity and joy." Keddie spoke of Stewart, saying "It's exhilarating to perform with her; I feel genuinely excited by it. That's a great feeling to have as an actor - when you really want to be working opposite someone and with someone. It doesn't get much more rewarding than that."
Offspring aired for 5 seasons from 2010 to 14 before returning to TV screens for a sixth season in 2016. With production of the new series underway Stewart spoke to Colin Vickery of News Corp, "I really didn’t think it would happen", Stewart said. "It was the best experience I’ve had in a show. You form such deep relationships with the people and also the characters. I feel really confident we’ll be able to deliver something great. I don’t think we’re going to coast on some sort of legacy. We’re really aware of that and all want it to be as fantastic and awesome as it can be. To get to walk around in Billie’s shoes again is fantastic". The seventh season of the show, including Stewart and other key cast members, screened in 2017. Writing in 'The Daily Telegraph', Colin Vickery reflected on season 7 with "this year...Billie, played by Kat Stewart, has had to endure a heartbreaking split with husband Mick (Eddie Perfect). Billie's rollercoaster life has showcased Stewart's comedic and dramatic talents like never before. No wonder many critics believe she is the best actor on Australian television." Stewart teamed with
Shaun Micallef in the murder mystery drama/comedy,
Mr & Mrs Murder on
Network Ten in 2013. The pair played Charlie and Nicola Buchanan, a husband and wife duo of industrial cleaners with an amateur interest in solving crimes. The two previously worked together on the satirical SBS newscast show
Newstopia and both have spoken positively of their on-screen chemistry and rapport From 2019 to 2023 Stewart appeared in the
Network Ten and
Paramount+ housemates' drama
Five Bedrooms co-starring with
Stephen Peacocke,
Hugh Sheridan,
Kate Jenkinson,
Doris Younane, Katie Robinson, Johnny Carr and Roy Joseph. In an interview with Debi Enker of
The Sydney Morning Herald, Stewart said of her character in
Five Bedrooms, "Liz is brave, but also fragile. I find her heart-breaking, but she can come off as a bit cold. I don’t think people will necessarily warm to her quickly. She’s complicated and I think that the older we get and the more that we’ve marched in the world with our armour, we don’t throw it off in a hurry. Liz’s got a lot of armour". Reflecting on the show itself Stewart commented, "It’s a challenge to make TV that’s fresh and of the time, because we’re competing with such brilliant overseas content. Going off the intelligence of the scripts, the heart and the humility and the humour, I feel like this is very much of the time. It feels fresh to me: it’s something I wanted to be a part of and something I would want to watch". In a review in
The Sydney Morning Herald in 2022 Melinda Houston concluded: "Not to mince words,
Five Bedrooms is one of the most criminally underrated shows on television right now....Fresh, relevant, smart, equal parts funny and heartbreaking, it’s an absolute delight." 2020 saw Kat Stewart appear as one of the featured celebrities in the 11th season of the Australian version of the television documentary reality genealogy series
Who Do You Think You Are? on
SBS. In 2023 Stewart appeared in
One Night on
Paramount+, alongside a cast including
Jodie Whittaker,
Nicole da Silva and
Yael Stone. In 2025 Stewart featured in a supporting role in the second series of the crime drama
Black Snow starring
Travis Fimmel on
Stan. On 23 February 2026, Stewart was named in the ABC drama
Fortitude Valley. Stewart's other TV credits include guest appearances in the
Nazeem Hussain sketch comedy series
Orange Is the New Brown in 2018,
True Story with Hamish & Andy on the
Nine Network in 2017,
No Activity on
Stan in 2015, ''
It's a Date and Jack Irish: Dead Point
in 2014, Camp'' on America's NBC in 2013, ''
Miss Fisher's Murder Mysteries in 2012, various roles in Newstopia on SBS in 2007–08, the BBC2/UKTV comedy series Supernova, as well as recurring roles on City Homicide, Kick, and Last Man Standing. Earlier in her career Stewart had guest roles on Blue Heelers, Stingers, CrashBurn, Something in the Air, The Secret Life of Us, and Fergus McPhail''. In 2015, Stewart appeared with close friend and mentor
Ailsa Piper in the contemporary interview program 'The Truth About Us' on
Foxtel's
Bio. channel.
Stage Kat Stewart has won acclaim on-stage in a range of dramatic and comedic roles. As an ensemble member of
Red Stitch Actors Theatre from 2002 to 2012 Stewart appeared in over a dozen plays for the company including
The Little Dog Laughed,
The Shape of Things,
Rabbit Hole,
Bug,
Dirty Butterfly,
Play About the Baby and
Loyal Women. In 2010 she appeared in the part of Tekla in an update of August Strindberg's
Creditors. In 2014, Stewart featured in
Melbourne Theatre Company's production of
The Speechmaker. The political satire was the first play from Australian filmmakers
Working Dog Productions and the writing trio of
Santo Cilauro,
Tom Gleisner and
Rob Sitch. When asked about the production and returning to the stage after a four-year break Stewart said "I’ve always wanted to work with [producers and writers] Working Dog. The script is engaging, smart, alarming and funny. I used to do six or seven plays a year. But I think you can lose your nerve if you leave it too long." Stewart had previously worked with MTC on productions such as
Festen in 2006 and 2008's
Frost/Nixon. In August 2016 she had a starring role on stage in the MTC production of
Ayad Akhtar's 2013 Pulitzer Prize winning play,
Disgraced, earning critical praise in the part of Emily. Stewart appeared in the 2019
Melbourne Theatre Company production of the
Simon Stephens' penned romantic comedy,
Heisenberg. The production was directed by Tom Healey and co-stars
Peter Kowitz. Stewart earned praise in the role of Georgie with Andrew Fuhrmann of the
Herald Sun saying, "This new MTC production is elegantly done, with a slow, almost meditative rhythm. And it features a wonderfully engrossing performance by
Offspring star Kat Stewart." He further summarised, "... really, the best reason to see this production is Stewart's finely modulated performance. Her Georgie is both utterly untrustworthy and deeply sympathetic." In 2022, Stewart returned to the stage in the
Melbourne Theatre Company production of Joshua Harmon's education satire
Admissions. The production was directed by Gary Abrahams and co-starred William McKenna, Heidi Arena, Simon Maiden and Deidre Rubenstein. Cameron Woodhead of
The Age described Stewart's performance as '...the glossiest possible portrayal of liberal officiousness and the cynical abyss her wokeness teeters into when the chips are down.' Stewart starred as Martha in three productions of ''
Who's Afraid of Virginia Woolf?, alongside the same cast including real-life partner, David Whiteley, as well as Harvey Zielinski and Emily Goddard. In 2023 and 2024 the quartet appeared in Red Stitch Actors Theatre productions, including a season at the Comedy Theatre in Melbourne, and followed by a Sydney Theatre Company run at the Roslyn Packer Theatre in late 2025. John Shand of the Sydney Morning Herald and The Age'' put the Sydney production in his top 5 of 2025, saying of Stewart "This is a performance that will throb in the memory bank long after age has pilfered most of them. Stewart’s light-switch mood changes are scary enough; her Martha’s rage is cyclonic, her intellect formidable, her capacity for alcohol bottomless and the terror on her face near the end heartbreaking."
Film Stewart appeared in
West of Sunshine, a movie directed by
Jason Raftopoulos and released in Australian cinemas in 2018. The urban drama also stars
Damian Hill, Ty Perham, Arthur Angel and
Kaarin Fairfax. In 2019 Stewart has a supporting role in
Little Monsters. The zombie comedy horror film, written and directed by
Abe Forsythe, premiered at the
Sundance Film Festival in January 2019 and stars 2013 Oscar winner
Lupita Nyong'o,
Josh Gad,
Stephen Peacocke and
Nadia Townsend.
Radio and podcasts In December 2020, Stewart co-hosted
How Big is My Trailer, an interview series bringing together two well known Australians in a "revealing and open-hearted conversation hour about the highs, lows and left turns of navigating a truly successful life in film, television and the arts." Stewart co-hosted with interviewer/producer Angela Pulvirenti and each episode paired some of Australia's leading creative talents including
George Miller with
Tim Minchin,
Asher Keddie with
Daina Reid,
Damon Herriman with
Emma Freeman,
Eric Bana with
Trent Dalton,
Eddie Perfect with
Tina Arena. ==Personal life==