Er stammte aus einer Brahmanen Familie aus Benares und war geschult in den Veden.
Später, wegen seiner Beziehung zu Vimala Thera, trat er in den Orden ein und lebte mit ihm. (Aber nach ThagA.i.377, wurde Vimala von Somamitta ordiniert). But finding Vimala given to sloth and laziness, Somamitta left him and joined Mahā Kassapa, under whose direction he soon attained arahantship. Later he visited Vimala and rebuked him. Vimala then put forth effort and became an arahant.
Somamitta was a householder in the time of Sikhī Buddha, and, very pleased with the Buddha, he picked some kimsuka-flowers from a tree and offered them to him (Thag.vs.147f ; ThagA.i.267f).
He is perhaps identical with Kimsukapupphiya Thera of the Apadāna. Ap.ii.435; but see ThagA.i.87.