The high-profile gathering will explore how to protect parliamentarians from online harm, and will convene for the first time in 2027.
It's the brainchild of Prime Minister Anthony Albanese and his UK counterpart Andy Burnham, who hatched the plan on the sidelines of the Commonwealth Heads of Government Meeting in Antigua and Barbuda.
"A toxic online environment is a threat to all Commonwealth democracies," the leaders said in a joint statement.
"Talented and principled people choose not to stand for election because of the hate they see their elected representatives and their families face.
"Addressing these harms requires collective action."
Violence against politicians has buffeted both countries.
On October 19, a car slammed into independent Victorian MP Helen Haines outside her electorate office in Wangaratta, in what authorities are treating as a deliberate attack.
Both her legs were amputated and she remains in hospital in a serious condition.
On July 9, Conservative MP turned Reform UK spokeswoman Ann Widdecombe died after being hit 21 times with a hammer in her home.
Dr Haines' alleged attack also drew comparisons to the 2016 murder of UK Labour MP Jo Cox, who was shot and stabbed at an event in her constituency.
Mr Albanese had previously called attention to Dr Haines at a speech to dignitaries in the Caribbean.
"It has brought home to us the urgent need to protect our elected representatives, so they can continue to do their jobs," he said.
His statement with Downing Street said women were being disproportionately targeted by the growing number of threats.
"We know that in Australia and the UK women parliamentarians are three times more likely to report receiving sexualised or gender-based threats," it read.
The leaders pledged to explore what protection could be offered by software tools being trialled in parliaments around the 56-member Commonwealth.
Absent from the leaders' statement was news of whether British backpackers would soon be moving from Bondi to the bush, as Mr Albanese tries to reinstate a regional labour requirement to reduce the influx of UK working holiday makers.
The prime minister raised the issue at the bilateral meeting with Mr Burnham, who is still mulling it over.
"They're (British backpackers) not benefiting from the experience of seeing the whole of Australia if they're just staying in Sydney and Melbourne," Mr Albanese told reporters in Antigua and Barbuda on Wednesday.
"I advocated why I think change is necessary, and put forward a number of options, and we'll work those issues through over coming weeks."
British backpackers are exempt from an 88-day rural work requirement.
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