Johnson is attending annual talks in Sydney between the British and Australian foreign and defence ministers.
Sydney: Britain plans to play a bigger role in Asia after Brexit, including deploying its military to the area if necessary, Foreign Secretary Boris Johnson said Thursday.
Johnson backed the campaign to quit the EU and said the decision had given his country the opportunity to "think afresh" about its international role, while maintaining close ties with its European partners.
"One of the purposes of my trip is to get over the message that we are now going to be more committed to the Asia-Pacific region and more committed to Australia," he told The Australian newspaper in a Sydney interview.
"One of the things I find everywhere I go is that people want more Britain, not less Britain. They want a Britain that is more engaged, not less engaged.
"When I talk about global Britain they genuinely see the point. This (Asia) is an area of fantastic growth. It's also an area of tension.
"People want the involvement of a country that sticks up for a rules-based international system, that is prepared to deploy its military in the area, as we are."
Johnson, who has also visited Japan and New Zealand on an Asia-Pacific swing, is attending annual talks in Sydney between the British and Australian foreign and defence ministers, focusing on security and trade.
High on the agenda is expected to be a British pitch to build Australia's next fleet of warships, with Spain and Italy also in the running for the lucrative deal to construct nine frigates.
Australia earlier this year detailed a massive Aus$89 billion (US$70.4 billion) shipbuilding strategy in the nation's largest peacetime naval investment.
It comes as Beijing flexes its muscle in the region through a military build-up in the contested South China Sea.
China asserts sovereignty over almost all of the resource-rich region despite rival claims from Southeast Asian neighbours and has rapidly built reefs into artificial islands capable of hosting military planes.
Johnson said Britain took "no position on the merits of the case," an approach echoed by Australia.
But he said it was clear "the law of the sea is there to be honoured".
"What people need is certainty and stability. We believe that legal certainty in the South China Sea is hugely important," he added.
"We don't want to see the militarisation of that area. We believe that for world trade to prosper there must be a fairness about the way sea lanes are going to operate."