The top prosecutor has decided not to take legal action against the boat owner who led a voyage to the disputed Diaoyu Islands in August.
A summons against Lo Chau for leaving Hong Kong waters without permission, issued by the Marine Department, was cancelled by Eastern Court on Wednesday.
The department said the director of public prosecutions felt cancelling the summons was the right course of action because a prosecution wasn't in the public interest.
But Lo and skipper Yang Kuang have been issued a warning to abide by the law in future.
The summons, issued on February 14 said Lo's vessel, Kai Fung No 2, left Hong Kong waters without permission on August 12.
Eight members of the Action Committee for Defending the Diaoyu Islands sailed to the disputed islands in the East China Sea to assert Chinese sovereignty. The chain is also claimed by Taiwan and Japan - which calls them the Senkaku Islands.
The activists made the first landing by Hong Kong activists in 16 years.
Committee member Tsang Kin-shing, who was on the boat in August, said earlier there were no grounds for prosecution. The boat was a licensed fishing vessel and did not need a permit to sail out of Hong Kong waters.
Lo and Tsang are on a trip overseas and couldn't be reached for comment.
The eight activists, two journalists and four crew members managed to evade marine police and an interception attempt by Japanese coastguard vessels as they approached the islands. Seven activists pitched the Chinese flag on the island.
All 14 were arrested by Japanese authorities and deported.