Chen Ping, Shanghai-born billionaire investor and publisher of political weekly iSun Affairs was beaten last night near the magazine's office in Chai Wan.
Chen, 58, was ambushed when he was getting into his car outside the Sino Favour Centre on On Yip Street shortly before 6pm. Police said he was attacked by two baton-wielding men aged between 20 and 30 years old.
The pair fled the scene after the attack. Chen's 38-year-old driver called an ambulance.
Chen remained conscious despite sustaining injuries to the head, arms and chest, and was taken to Pamela Youde Nethersole Eastern Hospital.
Officers from an Eastern district police team were investigating. No arrests have been made.
Chen told the South China Morning Post last night that he had been attacked and injured, but was not sure what kind of weapons had been used.
The former Communist Party think tank member founded iSun Affairs in Hong Kong as a website in August 2011, then turned it into a weekly magazine circulating in Hong Kong, Macau, Taiwan and Malaysia. It is banned on the mainland.
It has a reputation for being outspoken and publishes stories on sensitive mainland issues.
It received particular attention in Hong Kong after an issue in January carried an explosive interview with Lew Mon-hung, a former key supporter of Chief Executive Leung Chun-ying, who accused Leung of lying about how he had dealt with illegal structures at his home and said he regarded the pan-democrats as "the enemy".