Disclosed herein is new Viola cornuta plant named 'Sunvioki', which is a vegetative propagated variety, developed by specific hybridization between '9V-39a' and 'Alpine Sun'. 'Sunvioki' has a spreading habit with very long stem. The plant height is low. The branching is abundant. Flowers are vertically oblong and very small. The color of flower is brilliant greenish yellow with vivid yellow eye. The plant has a high resistance to cold, pests and diseases.