The park staffer was recovering well in hospital after the attack at Ocean Park, which has four giant pandas from China, park spokeswoman Christie Lau said.
Lau said park officials were still investigating the Nov. 30 incident involving the male panda, whose name, An An, means "peace" in Mandarin. Lau declined to provide further details.
A park visitor posted a video clip on YouTube that allegedly shows the post-attack scene, with the keeper in a green park uniform crawling out of the panda pen as the furry animal runs back into its den.
The mass-market Apple Daily newspaper quoted an unidentified park employee as saying the keeper did not follow proper protocol, which requires locking pandas in their sleeping dens before putting bamboo leaves in their habitat.
Although pandas look cute and cuddly, they are wild animals that can be violent when provoked or startled.
Last month, a panda bit a college student in the southern Chinese city of Guilin after the student went into the animal's enclosure and tried to hug it.
A gift from the mainland Chinese government, An An arrived in Hong Kong in 1999 with female consort Jia Jia from the southwestern province of Sichuan. Another two giant pandas were also moved to the territory last year to celebrate the 10th anniversary of this former British colony's return to Chinese rule.