Last month, Turnbull met the US president in New York to mend bridges, after the bad-tempered call early in Trump's tenure.
In a leaked audio recording that comes just months after a tetchy phone call between the two leaders rattled ties soon after Trump took power, Turnbull is heard making fun of the US president's idiosyncratic speaking style.
"The Donald and I, we are winning and winning in the polls," Turnbull said in a closed event for journalists in Canberra on Wednesday.
"We are winning so much. We are winning like we have never won before."
"We are. We are. Not the fake polls. Not the fake polls. They're the ones we are not winning in," he said to laughs from the audience at the Mid-Winter Ball, where politicians and Canberra journalists let their hair down.
"We are winning in the real polls. You know, the online polls. They are so easy to win."
Typically, the event is off-the-record, meaning journalists would not report on what was said, but a recording was leaked to the political editor at commercial broadcaster Channel Nine, who did not attend the soiree and decided to report it.
Last month, Turnbull met the US president in New York to mend bridges, after the bad-tempered call early in Trump's his White House tenure.
Trump reportedly exploded and cut short the call when he was told about a Barack Obama-era deal to move refugees from Australia to America.
The Australian leader appeared to make light of that icy conversation in the leaked recording.
"It was beautiful. It was the most beautiful putting-me-at-ease ever," he said.
In another leaked clip, Turnbull poked fun at the ongoing controversy surrounding the Trump administration's ties to Russia.
"I have this Russian guy. Believe me, it is true. It is true," Turnbull said.