Mr Kham was reunited with his family in Sydney on Tuesday after representations from the federal government - including by Prime Minister Anthony Albanese on a trip last month to Vietnam - led to his release.
Vietnamese police arrested the retired baker in January 2019 and a court later convicted him of terrorism, imposing a 12-year prison sentence.
The trial lasted a matter of hours and raised serious due process concerns.
The case was based on his affiliation with an opposition political party, Viet Tan, which operates lawfully Australia.
Mr Kham is scheduled on Wednesday to address media in Sydney with his lawyer and a representative from human rights group Amnesty International.
Mr Kham's wife and two children this week thanked their legal team and the Australian government for securing his release.
"We share this happy news that Chau Van Kham is well and has returned to his family today," the family said.
Federal minister Chris Bowen posted a photograph on Twitter with the freed man, writing: "Today is a good day".
Human Rights Watch says more than 150 political prisoners remain in detention in Vietnam for peaceful acts of free expression.
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