Senator Malcolm Roberts was elected by Queensland as a member of the anti-immigration One Nation party.
He believes climate change is a global conspiracy created by bankers seeking to establish a worldwide government.
Mr Roberts told the Senate "We need an OzExit" to escape the "unelected swill" of the UN.
"Australia's values and way of life are also at risk from insidious institutions such as the unelected swill that is the United Nations," he said.
"The EU is a template for total socialist domination of Europe through unelected bodies, such as the IMF, forcing their frightening agenda on the people. It is also the UN's template, and Australia must leave the UN."
He also quoted British comedian John Cleese, former US president Andrew Jackson and bush poet Banjo Paterson, and compared himself to Greek philosopher Socrates.
The senator also used his maiden speech to heap scorn on climate science, saying the UN's position was "absurd".
"It is basic. The sun warms the Earth's surface. The surface, by contact, warms the moving, circulating atmosphere. That means the atmosphere cools the surface. How then can the atmosphere warm it? It cannot. That is why their computer models are wrong."
The former mining executive's speech comes one day after independent Senator Derryn Hinch, a former radio shock jock, used his maiden speech to name a convicted sex offender under parliamentary privilege.
"We are not worried what the establishment says about us," Mr Roberts said.
"We are not here for the establishment. We are here for everyday people and our nation."
At one stage during the speech the party's controversial leader, Senator Pauline Hanson, appeared to shake her head and roll her eyes as Mr Roberts heaped praise on her.
Ms Hanson later posted a statement to Facebook to clarify her reaction.
"I wasn't rolling my eyes out of disrespect to Malcolm's kind words, I was simply embarrassed," she said.
'Go back to where you came from'
Ms Hanson, 62, who also delivered a speech to the senate on Wednesday, repeated her call for a ban on Muslim immigration.
"If we don't make changes now, have no doubt we'll be living under Sharia law," she said.
She also called for those who did not assimilate to Australia's culture to "go back from where you came from", according to The Sydney Morning Herald.
"I suggest you go back where you came from. I'll take you to the airport and wave you goodbye," she said.
A number of Green senators walked out of the chamber during her speech.