Yang Hengjun, a former Chinese diplomat turned online journalist and blogger, was last week formally arrested by Chinese authorities, seven months after he was detained in the country.
"We'll stand up for our citizen and we'll expect him to be treated appropriately and his human rights to be respected," Morrison told Channel 9 television on Thursday, saying suggestions that Yang was a spy for Australia were "absolutely untrue".
"We make no apologies for standing up for one of our citizens."
The arrest comes amid growing diplomatic tension between Canberra and Beijing, including accusations of Chinese meddling in domestic political affairs that China has denied.
Yang, whose legal name is Yang Jun, has been detained since January and has not been allowed access to his lawyers or family, although Australian embassy officials have meet with him, the Australian government has said.
The 53-year-old was formally arrested on August 23. Espionage is punishable by death in China.
Canberra has said Yang was being held in harsh conditions and that it expected him to be treated in accordance with human rights law. A Chinese foreign ministry spokesman said Australia should not interfere in its legal process.
Morrison said Australia would continue to raise its concerns over Yang's treatment.
"I mean, that's not interfering in the system," he said, adding he respected that China had its own legal system.
"But we do expect Australians, indeed all citizens, to have their human rights appropriately looked after."
Several Australians have faced jail time in China over the past decade, including the former head of global miner Rio Tinto's China iron ore business, Australian citizen Stern Hu, who served eight years after a conviction in 2010 for corruption and stealing commercial secrets.
More recently, 16 staff from Australia's Crown Resorts, including three Australians, were jailed for between nine and 10 months in 2017 and fined 8.62 million yuan ($NZ1.27 million) for promoting gambling to lure Chinese high-rollers to its casinos.
