The High Court on Thursday denied bail to People Power activist Tam Tak-chi, who has been charged with uttering seditious words and disorderly conduct.
Judge Maggie Poon made the ruling after a hour-long hearing.
Tam was challenging a decision by the Fanling magistracy earlier this month that denied him bail.
He will be remanded in custody until his next court appearance on November 17, as prosecutors prepared to transfer the case to the District Court.
Prosecutors allege that the People Power vice-chairman used slogans such as "Liberate Hong Kong" and "Five Demands, Not One Less", as well as anti-police slogans, at street booths between March and July.
The prosecution said the slogans were intended to bring hatred against the government and raised discontent among the public. Critics said Tam's case was politically motivated and seriously undermines freedom of expression.
The activist is the first person charged with sedition since the 1997 handover.