Iaroslav Ievhen Hrynevych was born in 1898 in Lviv to the family of Joseph, a teacher, and Katria (née Banakh), a writer. He graduated from the First Academic Gymnasium in Lviv in 1916 and joined the Ukrainian Sich Riflemen. Hrynevych took part in the battle for Lviv during the Ukrainian–Polish War. In 1919, Hrynevych joined the Ukrainian Halyts’ka Army, and after being wounded in 1920, he was relieved of active military service.

He later enrolled at the University of Krakow, where he studied law. In 1935, he opened a law practice in the town of Nadvirna and in 1940, he moved to Hrubieshov in Kholmshchyna, where he defended the Ukrainian population against both the German administration and Polish authorities. In 1943, he relocated to Bolekhiv in Halychyna and continued his legal practice. There, he became head of the Ukrainian Aid Committee. He was arrested by the German Gestapo but managed to secure his release and subsequently immigrated to the West.

In 1949, Hrynevych arrived in the United States. While living in Jersey City, New Jersey, he founded the Ukrainian Credit Union Self-Reliance and served as its first president. He later moved to New York, where he worked as a contributing editor for Visnyk OOChSu, Natsional’na Trybuna, Novyi Svit, and Shliakh Peremohy, and became a member of the Association of Ukrainian Journalists in the USA.

In 1949, he became a founding member of the Organization of Ukrainian War Veterans in America. In 1952, he became a member of the Shevchenko Scientific Society (Sarcelle branch). From 1956 to 1957, he served on the executive board of the Ukrainian Literary Art Club in New York, and in 1965–1966, he was elected president of the New York branch of the Ukrainian Congressional Committee.

Hrynevych was the author of the play Nastup na Birchu (about the Ukrainian Insurgent Army), the biographical work Katria Hrynevycheva, and the collection of articles and documents Dolia Ukrainy na mytarstvakh, among other works. He died on March 25, 1978.