Oona Kauste (born 4 January 1988, in Espoo) is a Finnish curler from Helsinki.

In the semifinals, she lost to Scotland's Eve Muirhead, but rebounded to win the bronze medal against Denmark's Lene Nielsen.

Kauste and partner Tomi Rantamäki represented Finland at both the 2016 and 2017 World Mixed Doubles Curling Championship.

In 2016, the pair won their group with a 6–0 record, and made it to the quarterfinals where they lost to Russia.

Their pair of seventh-place finishes would qualify the team to represent Finland in the 2018 Winter Olympics.

She attended the International Maker Academy and the Omnia Vocational College.