Krista Mikkonen was born in the town of Hamina in south-eastern Finland. She is married to Ville Vuorio and they have three sons. Mikkonen joined the Green League during her university studies. The first time she was elected to the Joensuu City Council was in 1996, and she has served as a Council Member since 2005. She was the Deputy Party Leader of the Green League in 2011–2015 and, before that, she served in different bodies of the party. In the parliamentary elections of spring 2015, Mikkonen was elected to Parliament, where she was the first MP representing the Greens from the Savo-Karelia electoral district. In 2016–2019 she chaired the Green Parliamentary Group. Mikkonen was again elected to Parliament in spring 2019. In politics her particular focus has been on the environment, biodiversity, education and equality, and on combatting poverty.