A Professor of Political Economy at Sofia University from 1910 onwards, he took a leading role in the overthrow of the government of Aleksandar Stamboliyski in 1923 and was chosen to head the coalition that succeeded the deposed Premier. He became Prime Minister of Bulgaria on 9 June that same year and continued in the role until 4 January 1926. His Premiership was marked by deep internal struggles with the Bulgarian Communist Party, which Tsankov repressed mercilessly, declaring martial law and outlawing the Communists in 1925 following an attempt on Tsar Boris's life and a bomb attack on the St Nedelya Cathedral. A brief invasion by Greek troops followed and, although they did not stay long following condemnation by the League of Nations, the country was left crippled by debt and Tsankov was removed from office after failing to secure a loan for the country.
After being removed from the political mainstream, Tsankov began to develop and admiration for Fascism and soon became a supporter of Adolf Hitler. In 1932 he set up his own National Social Movement largely in imitation of the Nazi Party. The movement proved fairly unimportant (although it did represent a further fragmentation of the governing coalition), lacking the support of Zveno and failing to secure Nazi approval, which was largely reserved for the Union of Bulgarian National Legions. Nonetheless, Tsankov was appointed by the Nazis in 1944 as Prime Minister of the Bulgarian Government in Exile set up in Germany. After the Second World War Tsankov fled to Argentina and died in Belgrano, Buenos Aires in 1959.