Osaka made her Hopman Cup debut in 2018 with Yūichi Sugita. Japan was making their first appearance at the exhibition tournament since 2001. They were grouped with Switzerland, the United States, and Russia, and lost all three of their ties. Osaka's only match win came in singles against Russian Anastasia Pavlyuchenkova. She also had a big highlight in the mixed doubles match against Switzerland when she served an ace past Roger Federer.