Alma Ilona Pöysti (born 16 March 1981) is a Finnish actress. She is the daughter of director Erik Pöysti and granddaughter of Finnish actors Lasse Pöysti and Birgitta Ulfsson. Pöysti has also lived and worked in Sweden. Pöysti studied at the University of the Arts Helsinki from 2003 to 2007, then worked at the Swedish Theatre and the Finnish National Theatre.

In 2020, she played Tove Jansson in a biopic titled Tove. In 2023, she was nominated for the Golden Globe Award for Best Actress – Motion Picture Comedy or Musical for Fallen Leaves.