He settled in Trabzon where he worked as a lawyer from 1889 to 1895.[2][4] During his career he defended Armenians imprisoned for political activity.[5]
He was imprisoned during the Hamidian massacres in 1895.[2] In 1897, after spending thirteen months in prison, he escaped and settled in Batumi, ultimately moving to Tiflis.[1][6] There Shahrigian continued his legal career, working in association with Alexander Mantashev.[1]
On 25 July 1897, he left to Salmas, Persia in order to coordinate the Khanasor Expedition organized by the Armenian Revolutionary Federation.[2]
He participated in a 16–26 January 1898 congress of ARF Eastern Bodies members in Tiflis. There he served on the Potorig Committee from 1901 to 1903.[3] Shahrgian and Avetik Sahakyan were responsible for ARF operations in the region of Baku (Voskanapat) and northern regions of Russia.[7][full citation needed]
"The future, then, lies not in fusion – assimilation – but in a policy of unity, or more correctly, in a policy of pluralistic unity. Erase variety in nature, in the universe, make the universe uniform, and you will have erased the beauty of nature, its harmony, its life. Variety in nature, which seems to put every element at odds with another, actually, through harmony, forms the greatness of the perpetual motion of the universe."
—Harutiun Shahrigian in Mer Havadke (English: Our Credo)[2]
From 1905 to 1906 he organized the transportation and delivery of ammunition to front line positions to assist in self-defense efforts during the Armenian–Tatar massacres of 1905–07.[2][8]