He became a political figure in 1884 when he was appointed Minister of Justice in the cabinet of Petko Karavelov, also holding the position under Archbishop Kliment Turnovski.

His anti-Russian rhetoric impressed Ferdinand who worked closely with Radoslavov in shaping foreign policy.

He secured a large loan from Germany and Austria-Hungary in July 1914 but also managed to delay Bulgarian entry into the War.

As prime minister he oversaw the liberation of Southern Dobruja and the occupation of Northern Dobruja in 1916 with the aid of German General August von Mackensen, although the move lost him some support from the German government as they wanted some of the territory for themselves.

[4] His government remained in office until June 1918, when the more moderate Aleksandar Malinov was recalled in the hope of brokering a favourable peace deal, with Radoslavov blamed for the failure of Bulgaria to gain full control of Northern Dobruja in the Treaty of Bucharest (the southern part of Northern Dobruja was ceded to Bulgaria, while the northern part of the region was placed under joint Bulgarian, Turkish, German and Austrian-Hungarian administration).