In November 2016, de Geus was selected for the 2016 Junior World Cup, where the team finished seventh. He made his debut for the senior national team at the age of 18 in a test match against South Africa in 2017. He was part of the Dutch team that won the silver medal at the 2018 World Cup. In June 2019, he was selected in the Netherlands squad for the 2019 EuroHockey Championship. They won the bronze medal by defeating Germany 4–0. He was named the under-21 player of the tournament. In December 2019, he was nominated for the FIH Rising Star of the Year Award.