Greens Senator Scott Ludlam, who attended the negotiations in New York, said it was "an incredibly powerful moment".
"It's the large majority of the world states telling the nuclear weapons states that 'time's up', that it's time things changed," he said.
More than 120 countries on Friday approved the first-ever treaty to ban nuclear weapons at a UN meeting in New York boycotted by all nuclear-armed nations.
Australia did not play any part in shaping the treaty.
Campaigners against nuclear weapons are urging the Australian government to stop clinging to the belief the country will be protected by the US having weapons of mass destruction.
Doing so sends the wrong signal to countries like North Korea at a time when the world is grappling with the possibility of the hermit nation developing nuclear weapons capable of hitting Australia or the United States, they say.
The International Campaign to Abolish Nuclear Weapons (ICAN) wants the Turnbull government to sign Australia up to a new treaty to ban nuclear weapons during the United Nations general assembly leaders week in September.
"There are people in Canberra and elsewhere who believe that Australia is protected by US nuclear weapons," ICAN Asia-Pacific director Tim Wright said.
"If we're saying nuclear weapons are essential for our security, then how can we say that North Korea shouldn't rely on nuclear weapons also?
"It's an incitement to proliferate."
Senator Ludlam said defusing the situation is the best answer, and criticised G20 members for not using the summit to discuss the issue further.
"I think it could've been a great opportunity, but there is no doubt that it was an opportunity squandered."
The treaty will be open for signatures as of September 20, and will come into force once 50 nations have ratified it.
Mr Wright believes it will be difficult for Australia to resist the clear international movement on the ban for too much longer, citing domestic support for the policy.
Within hours of negotiations concluding, a joint statement from the United States, Britain and France rejecting the treaty was issued.
They said the treaty "offers no solution" to either North Korea, nor to any other security challenges.
Senator Ludlam has described it as misguided.
"The logic in there is hideously flawed", he said.
"We know we've got a steep hill to climb but the alternative is quite literally unthinkable."
-- With AAP
