Harmer's journalistic career took her to Melbourne, where she worked for The Sun News-Pictorial on the rounds of transport, urban affairs and state politics.

Harmer left The Sun News-Pictorial and worked part-time at the Melbourne Times, while performing as a stand-up comedian in her days off.

[1] She is acknowledged as the first Australian woman to enter the all-male domain of stand-up comedy in the 2015 ABC TV series Stop Laughing...This Is Serious.

She then joined the satirical political TV series The Gillies Report, along with John Clarke, Phillip Scott, Tracy Harvey, Patrick Cook and Jean Kittson.

Harmer went on to host ABC TV's, The Big Gig, including, among others, performers Glynn Nicholas, Rod Quantock, Greg Fleet, Jean Kittson and the Doug Anthony All Stars.

She also hosted her own ABC TV talk series In Harmer's Way, with comedians Greg Fleet, Andrew Goodone, Simon Rogers and Tim Smith.

Harmer also appeared on the Ben Elton show Friday Night Live with Dame Edna Everage and the Doug Anthony All Stars.

[11] In 1993, Harmer joined 2Day FM, co-hosting the highly rated breakfast radio show The Morning Crew for 11 years.

[14] On 1 October 2021, Harmer and Buck announced via an ABC News story that they were leaving the morning program after working together for three years, stating that they decided to "go out on a high".

Harmer hosted the Logie Awards of 2002, and was caught up in widespread media criticism of the event, with some focusing on her personal performance.

Harmer wrote many of the episodes, acted as a creative producer on the series, and even made a cameo appearance as Astrid the Dream Fairy.

[35] Harmer told the ABC Q&A program in November 2015 that her politics sounded "like an old fashioned socialist", that she objected to trends towards privatization of public assets, and that the GST is not fair.

[36] In a 2014 piece for the Herald, Harmer cautioned against being too dismissive of opposing political views: "right and left need each other to progress, we should be more humble about our supposedly deeply-held beliefs and not so quick to label our opponents as either carelessly ill-informed or purposefully evil.

[38] Harmer wrote in 2016 that acceptance of "gender fluidity" could be one of the "best things" to happen in her lifetime, and that "I believe, with all my heart, that we exist on a dynamic spectrum of sexuality and that labels are at best useless, at worst tragically destructive.

"[40] In 1993, she participated in a comic debate "Does Australia need the Royal Family", arguing the case for the negative alongside future Liberal leader Malcolm Turnbull and Labor politician Graham Richardson.

"[40] In an article written for The Sydney Morning Herald in March 2013, Harmer described herself as "born into an atheist household", but said she attended Church of England Sunday school for a time until her father declared himself "humanist".

The sad, godless orphans who can't pass a church or temple without entering to light a candle or offer a flower.

"[43] In an essay in Destroying The Joint: Why Women Have To Change The World edited by Jane Caro, Harmer wrote that her two children have been confirmed into the Catholic Church.

[44] She is a co-founder, of the Manly Warringah Sea Eagles's Angels, the women supporters' group for the local rugby league club.