Dong Guangping, a former policeman who was imprisoned for his activism, was found by South Korean authorities on Monday night drifting off the country's west coast on a 3.3-metre rubber boat with a 9.9-horsepower engine, according to police.
He was taken to shore for questioning on suspicion of violating immigration laws.
The man's lawyer, Kim Joo-kwang, confirmed his identity to AFP. He declined to say from where Dong launched his boat.
Dong, 68, is known for his opposition to the Chinese Communist Party (CCP) and his advocacy for political reform and human rights.
He was dismissed from his work as a policeman after signing a petition a decade after Beijing's 1989 Tiananmen Square crackdown, according to US-based advocacy group Human Rights in China.
He later spent about three years in prison from 2001 for "inciting subversion of state power", UN experts said, and was detained again in 2014 over Tiananmen-related activities.
Dong fled to Thailand with his family, who later resettled in Canada as refugees, but Thai authorities handed him over to Chinese police in 2015 despite his UN-recognised refugee status.
Dong's attorney told AFP his client's current situation is "highly likely to be a political asylum case".
Full protection
South Korea has granted political asylum to a relatively small number of applicants since it began formally processing refugee claims in 1994, with an overall recognition rate in the low single digits despite tens of thousands of applications.
Critics say the low approval rate reflects strict screening and lengthy procedures, while the government maintains that decisions are made on a case-by-case basis and take security considerations into account.
Seoul's foreign ministry did not respond to a request for comment.
The opposition People Power Party has called on the government to offer Dong "full protection".
"It should take swift humanitarian measures to ensure that he can safely travel to Canada, where his family is anxiously awaiting him," party spokesman Choo Hyun-chul said in a statement to AFP.
"This is a matter of a fundamental responsibility as a liberal democratic state."
In August 2023, Kwon Pyong, a Chinese dissident, fled China on a jet ski to South Korea, where he was later convicted of illegal entry and given a suspended prison sentence.
