Protesters blocked roads and paralysed train services at peak times on a day of action across the city.
More than 200 flights were cancelled as the protests entered their ninth week.
Hong Kong's leader, Carrie Lam, has pledged to restore law and order, rejecting calls for her resignation.
Initially the demonstrations, which began on 9 June, focused on a controversial extradition law, which would have allowed the transfer of suspects to mainland China. However, the protests have now become a wider challenge to Beijing's authority.