Milan Ciganovic was born in Bosnia-Herzegovina in 1888. He moved to Belgrade where he became a senior member of the Black Hand group. Ciganovic worked closely with Colonel Dragutin Dimitrijevic, the chief of the Intelligence Department of the Serbian General Staff. As a cover for his espionage activities, Ciganovic worked as a minor official with the Serbian State Railways.

It is believed that Ciganovic played a major role in the conspiracy to assassinate Archduke Franz Ferdinand. On 27th May, 1914, he supplied Nedjelko Cabrinovic, Gavrilo Princip and Trifko Grabez with four revolvers, six bombs and the vials of poison. There is also evidence to suggest that it was Ciganovic who informed Nikola Pasic, the prime minister of Serbia, about the planned assassination.

On Sunday, 28th June, 1914, Franz Ferdinand and Sophie von Chotkovato were assassinated by Gavrilo Princip. Princip and Nedjelko Cabrinovic were captured and interrogated by the police. They eventually gave the names of their fellow conspirators. Muhamed Mehmedbasic managed to escape to Serbia but Vaso Cubrilovic, Danilo Ilic, Veljko Cubrilovic, Cvijetko Popovic and Misko Jovanovic were arrested and charged with treason and murder.

Several members of the Black Hand group questioned by the Austrian authorities claimed that three men from Serbia, Ciganovic, Dragutin Dimitrijevic and Major Voja Tankosic, had organised the plot. On 25th July, 1914, the Austro-Hungarian government demanded that the Serbian government arrest the men and send them to face trial in Vienna.

On 25th July, 1914, Nikola Pasic, the prime minister of Serbia, told the Austro-Hungarian government that he was unable to hand over these three men as it "would be a violation of Serbia's Constitution and criminal in law". Three days later Austro-Hungarian declared war on Serbia.

The Serbian government sent Ciganovic to the United States for the duration of the First World War. He returned in 1919 and received a small grant of land from the government, married and settled down. Milan Ciganovic died in 1927.