Guardian Australia’s editor-in-chief, Lenore Taylor, has resigned after 10 years in the role, credited with taking the fledgling news organisation from a tiny startup to the fourth most-read news website in the country.

Taylor joined the global media organisation Guardian News and Media in 2013 as founding political editor of the new Australian venture, rising to editor-in-chief in 2016.

A former Sydney Morning Herald political journalist, Taylor was hired by the then Guardian Australia editor-in-chief Katharine Viner along with her press gallery colleague Katharine Murphy from the Age, as deputy political editor.

Viner, the Guardian’s global editor-in-chief, credited Taylor with making the Australian arm of the organisation “a force to be reckoned, sometimes through sheer strength of will”.

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“Her hard work, commitment, editorial rigour and political insight have helped deliver journalism that sets the national agenda and driven much admiration from our ever-expanding audience,” Viner said.

“She leaves Guardian Australia very well-placed to navigate to the next stage of its evolution, as both a distinct edition and a crucial part of the Guardian’s global operation. I want to thank Lenore for her enormous contribution to Guardian Australia over the past 13 years.”

Taylor has overseen the rapid growth of the news site, in both influence and reach, and across podcasts, video and social media. It now employs 140 editorial staff across the country and is supported by reader contributions and advertising.

Guardian Australia has won 12 Walkley awards for its reporting on the environment, politics, social affairs, Indigenous issues and commentary under Taylor’s leadership.

According to the latest Ipsos Iris news ranking, Guardian Australia is the fourth most-read news site in the country with a unique audience of 8.4 million, ahead of established newspaper mastheads the Sydney Morning Herald, the Age and the Australian.

Taylor said she had been musing on the decision for some time, saying 10 years is a long time in a demanding job.

“But there’s always been another challenge, another big story or another reason to defer it,” she said. “There’s always the next thing in a job that is so utterly exhilarating and all-consuming. But it is also utterly exhausting.

“When I started as editor the feedback I heard most often from readers was ‘thank goodness the Guardian has come to Australia’. What I hear most often now is ‘I can’t imagine Australia without the Guardian’. Neither can I.”

Taylor won two Walkley awards for journalism and is a two-time recipient of the Paul Lyneham award for excellence in press gallery journalism.

She is the country’s current longest-serving newspaper or news site editor and the longest-serving female lead editor in Australia.

The senior managing editor of the Guardian in London, David Munk, will be acting editor while Viner runs an open process to appoint a new editor. Munk is a previous deputy editor of Guardian Australia.