Johnson's visit comes after relations between Britain and Hong Kong have been increasingly strained since 2020 when Beijing imposed a national security law in the former colony.
Johnson also wrote in an opinion piece in the South China Morning Post on Tuesday that Britain would engage with China and Hong Kong where interests converge but would stand up for its values "and be clear about our right to act when Beijing breaks its international commitments or abuses human rights".
Hong Kong and Beijing have said previously that Britain had no rights over the city under the joint declaration that laid the blueprint for how the city would be ruled after its 1997 reunification with China. When asked about Johnson's visit, Hong Kong's chief executive John Lee said on Tuesday he welcomed foreign officials to come to Hong Kong to promote business, trade and people-to-people relationships, as Hong Kong has always relied on international and regional cooperation for its success.