Koreichuk emigrated to Canada, apparently, in the spring of 1913. He emigrated because of poverty, Austrian repression, and chronic respiratory illness.[2] He was one of the most experienced labour organizers in North America from Ukraine and quickly became active in the Federation of Ukrainian Social Democrats (FUSD) in Montreal, Quebec. When the FUSD renamed itself the Ukrainian Social Democratic Party of Canada (USDPC) and moved its headquarters to Winnipeg, Manitoba in January 1914, Koreichuk followed. In Winnipeg, he became involved in the local Ukrainian movement, serving as the first presidentof the Volodymyr Vynnychenko Drama Circle and contributing to the Ukrainian newspaper Robochyi narod while speaking at events organized by the USDPC.[2] While working with the USDPC in Western Canada in the spring of 1915, he was interned with other unnaturalized Ukrainian workers in the Crowsnest Pass.[3] Afterwards, he ran a Ukrainian workers' bookstore in Winnipeg due to his worsening health, but in 1917 in Ottawa he spoke at a May Day rally regarding the recent Russian Revolution and in 1918 in Welland he organized a workers' night school.[2] In 1918, he moved to rural Alberta for health reasons and also to avoid intensified repression.[2]
On September 5, 1919, Koreichuck was arrested with making "seditious speeches". This came after he was denounced by the local Ukrainian clergy and businessesman in Vegreville, who feared labour unrest and Bolshevism.[2] Still an unnaturalized Austro-Hungarian subject, he was sent to an internment camp in Vernon, British Columbia.[2] After a few weeks, he died of tuberculosis.