"This is an important port, it's our gateway to Asia and it's strategically very important," he told SBS News on Monday.
"We now face a period of geopolitical uncertainty so I think it would make sense to have this very important port in Australian hands."
Mr Champion accused the NT government of considering commercial interests above national security when it signed the 99-year lease with Chinese company Landbridge, in a deal worth $550 million in 2015.
Prime Minister Scott Morrison distanced the federal coalition from the deal on Monday.
"The commonwealth government never approved that sale," he told reporters.
US missiles in Darwin ruled out
The move comes as Australia hosed down speculation the United States was seeking support from Canberra to put ground-based missiles in Darwin.
Mr Morrison said the US had not requested a missile deployment in northern Australia, while Defence Minister Linda Reynolds also denied the issue was raised during a meeting on Sunday with newly-appointed US Defence Secretary Mark Esper.
"It's not been asked of us, not being considered, not been put to us. I think I can rule a line under that," Mr Morrison told reporters in Brisbane.
After the Darwin Port lease was approved, the federal government tightened rules around foreign investment to ensure national security issues are considered.
"We worked with the state and territory governments to ensure that in a situation like that again, it wouldn't be left to the sole discretion of the state and territory government."
Finance Minister Mathias Cormann also ruled out the prospect of nationalising the port.
"We are not considering either the purchase of Darwin Port by the federal government or any proposition of a forced change of ownership," he told AAP.
Mr Champion urged the government to consider buying back the port, arguing it would not be the first time an Australian government has nationalised an asset.
The port lease sparked concerns within Defence about Landbridge taking control of what could be considered a strategic asset.
But Mr Champion doesn't believe nationalising the port would anger China, which is Australia's largest trading partner.
"I don't think it needs to have any effect on any of the relationships with countries we have to the north, our trading partners, our friends, our allies. This would simply be us making a decision in our national interests."
One Nation leader Pauline Hanson has grave concerns about Chinese ownership of Darwin's port.
"I think one day they'd love to have their hands on Australia and they're slowly taking it, not by stealth, by cunning," she told Nine's Today program.
"You can see they're strategically setting themselves up in the islands around Australia as well."
Senator Hanson said she believed China's growing population was looking for somewhere to move and had "their eyes on Australia".
Additional reporting by AAP