Jérôme Hugonot, a veterinarian with dual French and Australian citizenship, has been freed "in good health" after being taken hostage in Chad earlier this week.
Chad interim President Mahamat Idriss Deby announced the news on Sunday via Twitter, without providing any details on how it was achieved.
"I am delighted with this happy ending," Mr Derby said.
A spokesperson for the Department of Foreign Affairs and Trade said the Australian government welcomed the news of Mr Hugonot's release.
"Due to our privacy obligations we are unable to provide further details," the spokesperson told the ABC.
Mr Hugonot was working for the Sahara Conservation Fund in Wadi Fara providence, near Sudan, when he was abducted on Friday by unknown kidnappers, according to Chadian government authorities.
A number of armed groups operate along the Chad-Sudan border.
The Sahara Conservation Fund and its partners have spent years in Chad working to reintroduce a species of desert antelope known as the scimitar-horned oryx.
"It is with great joy that we learned Hugonot was freed earlier today," said John Watkin, CEO of SaharaConservation.
"It is a relief for his family and for all those who actively worked for his release.”
The organisation said he was "found in good health and is now in safety".
"SaharaConservation would like to thank all those who participated in the release process and in particular the Chadian and French Authorities who mobilised massively to free him," the conservation organisation said in a statement.
No details have been given about who kidnapped Mr Hugonot or how the release was obtained.
The individual had been kidnapped on Friday "in the afternoon of 28 October", Chadian authorities said Saturday, adding they had "mobilised all security and human means to get hold of the kidnappers".
"The hostage was released in the province of Tibesti (North), in an area bordering Niger and Libya by our defence and security forces," Ayoub Abdelkerim Abdoulaye, governor of the eastern province of Wadi Fira where the abduction took place, told AFP.
Prime Minister Saleh Kebzabo said Mr Hugonot had since been "taken to safety in good health".
"I congratulate our Defense and Security Forces for this prompt and successful action," he wrote.
The French foreign ministry also announced the release in a separate statement.
"France thanks the Chadian authorities that worked for this release," the ministry said, also without giving further details.
The deputy spokesperson of the Ministry of Europe and Foreign Affairs expressed relief over Mr Hugonot's release.
"France thanks the Chadian authorities who worked for his release," the spokesperson told the ABC.
"The services of the Ministry of Europe and Foreign Affairs, both in Paris and in N'Djamena, remain mobilised to provide all their support to our compatriot and his family."
Mr Hugonot migrated from France to Australia in 2002 and worked as a vet in four states in the country before travelling to Chad in 2021.
Chad has been chronically unstable since it gained independence from France in 1960.
Last week, at least 50 people were killed and nearly 300 injured in protests in the capital as hundreds took to the streets to demand a quicker transition to democratic rule.
ABC/wires
