Having fled from Russia not long after the October Revolution, he settled in the Kingdom of Serbs, Croats and Slovenes, where he became a professor at the University of Belgrade Faculty of Law (1920-1936).
After the end of World War II he briefly served as the first dean of the Sarajevo Law School (1947-1949), before Communist repression forced him to emigrate to Switzerland, where he worked as professor of Slavic studies at the University of Geneva (1951-1961).
From 1920 to 1946 he was a professor at the University of Belgrade, where he received his doctorate in 1928 for his thesis on the 14th-century king and legislator Stefan Uroš IV Dušan of Serbia.
After the Second World War he was named dean of the newly created University of Sarajevo Faculty of Law from 1947 to 1949, but after the complete communist takeover in the Yugoslavia, the Tito–Stalin split and the beginning of Informbiro period, he and his wife were arrested and imprisoned in 1949.
After their release, Soloviev and his family moved abroad once again, this time to Switzerland, where he became professor of Slavic studies and Byzantine history at the University of Geneva (1951–1961).