The 24-year-old from Runcorn became Britain's first champion in the event's 17-year history with last year's win.
After taking gold in the season-opener in Switzerland, Coxsey reversed the outcome from the last event in China by pipping Janja Garnbret to gold.
Coxsey leads the Slovenian in the overall rankings, with four more events to take place before August.
Japan's Miho Nonaka claimed bronze, with Britain's Michaela Tracey 11th.
Sport climbing - which includes bouldering - is one of five new sports confirmed for the 2020 Tokyo Olympics.
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WATCH: How Shauna Coxsey became the UK's first bouldering world champion
Shauna Coxsey continued her Bouldering World Cup title defence by claiming gold in the third event of the season.