He was a professor of history and one of the founding members of the Georgian Academy of Sciences.

Janashia was born in 1900, in Makvaneti in the southwestern Georgian province of Guria.

His father, Nikoloz Janashia (1872-1918), was an educator and ethnographer, born in Abkhazia.

In the 1940s, he organized archaeological excavations in Mtskheta and Armazi in eastern Georgia.

A full collection of Janashia's works was published in four volumes in Tbilisi between 1949 and 1968.