Valkov also graduated from an artillery academy and at the beginning of the 20th century was the only Bulgarian army officer who attended two higher education institutions.

As its head, Valkov took part in the Bulgarian coup d'état of 9 June 1923, in which they overthrew Prime Minister Aleksandar Stamboliyski.

He oversaw the repression of leftist organizations after the September Rebellion in 1923 and the assassination attempt on Tsar Boris III of Bulgaria two years later.

In October 1925, at the time of the Greco-Bulgarian conflict in the Petrich district, General Valkov used diplomatic rather than military means to restore the status-quo.

At a time when negotiations were underway regarding Bulgaria's representation in international organizations, the government demanded the Valkov resign because of his reputation of being an opponent of democracy.