Rosos was born in the village of Moschochori, Florina, Greece in 1941. During the civil war in Greece in 1948 he was evacuated in Czechoslovakia as a refugee child. Rossos studied at primary school in Sobotin and Technical School in Prague. In 1958 he moved with the rest of his family to Canada. He graduated at high school in Toronto. Rossos earned a bachelor's degree in history at Michigan State University in 1963. Rossos graduated postacademic degree and was awarded by the University of Stanford with a Ph.D. in 1971. Since then he has worked at the University of Toronto, and in 1982 became Professor there. Rossos is author of a monograph on Russian foreign policy on the Balkans ("Russia and the Balkans: Inter-Balkan Rivalries and Russian Foreign Policy, 1908-1914"). At the end of 2008 was issued his book "Macedonia and the Macedonians: A History". Rosos is adherent of the views espoused by the national historiography of the Republic of Macedonia.
- Македонска енциклопедија. Скопје, 2009, т.ІІ, 1282.
- Recension from Professor Stefan Troebst about Rossos's book: Macedonia and the Macedonians. A History, 2008
- The British Foreign Office and Macedonian National Identity, 1918-1941 (Slavic Review, 1994)
- Incompatible Allies: Greek Communism and Macedonian Nationalism in the Civil War in Greece, 1943-1949
- Macedonia and the Macedonians: A History (2008)
- "The Disintegration of Yugoslavia, Macedonia's Independence, and Stability in the Balkans." In War and Change in the Balkans: Nationalism, Conflict, and Cooperation, edited by Brad K. Blitz. Cambridge: Cambridge University Press, 2006.
- "Great Britain and Macedonian Statehood and Unification, 1940-49," East European Politics and Societies 14.1 (Winter 2000): 119-142.
- "Incompatible Allies: Greek Communism and Macedonian Nationalism in the Civil War in Greece, 1943-1949," Journal of Modern History 69.1 (March 1997): 42-76.
- "The British Foreign Office and Macedonian National Identity, 1918-1941." In National Character and National Ideology in Interwar Eastern Europe, edited by Ivo Banac and Katherine Verdey. New Haven: Yale Center for International and Area Studies, 1995.
- "The Macedonians of Aegean Macedonia: A British Officer's Report, 1944," Slavonic and East European Review 69.2 (1991): 282-309.