Son of the Epirus fighter Ioannis Giannikostas. He graduated in 1852 from the Evelpidon School with the rank of second lieutenant. In 1863 he fought against the Turks in Epirus. He then took part in the unfortunate war of 1897, as commander of the 8th infantry regiment at Reveni and Velestino, under Brigadier General K. Smolensky, where he distinguished himself.

He was retired due to age with the rank of Lieutenant. He was elected MP for Attica in 1899 and served his country faithfully. He participated actively with other Masons (I. Dragoumis , Ath. Souliotis, Kl. Skalieris etc.) in supporting the Eastern idea , and the equal cooperation of the peoples of the Balkan and Near East.

He was an Additional Grand Master.