He was a passenger in the car carrying Archduke Franz Ferdinand of Austria and his wife Duchess Sophie of Hohenberg when they were assassinated in Sarajevo on 28 June 1914.

Serving as inspector general in Sarajevo in 1910, he was appointed Bosnian governor (Landeschef) the next year, holding both civil and military offices.

An attack on the life of former governor Marijan Varešanin in 1910 and several rumours of future assaults (leaked by Serbian prime minister Nikola Pašić) did not keep the archduke from a public appearance in Sarajevo, backed by Potiorek, who worried about his own prestige.

On 28 June the royal couple arrived from Ilidža by train and went to Philipovic army camp where Franz Ferdinand performed a brief review of the troops.

Potiorek was waiting to take the royal party to the city hall (present-day National and University Library of Bosnia and Herzegovina) for the official reception.

Franz Ferdinand, his wife and several officials switched into a six-car motorcade driving down Appel Quay along Miljacka River without further security measures.

Potiorek was in the third car, a Gräf & Stift Double Phaeton, open six-seater driven by Leopold Lojka, together with the owner Count Harrach and the royal couple.

A furious Franz Ferdinand, after attending the official reception at the City Hall, asked about visiting the members of his party that had been wounded by the bomb.

A member of the archduke's staff, Andreas von Morsey, according to his own accounts suggested this might be dangerous, but Potiorek replied "Do you think Sarajevo is full of assassins?

On the way to the hospital, Lojka took a right turn opposite the Latin Bridge, where one of the conspirators, Gavrilo Princip, was standing outside the corner delicatessen at the time.

When the assassination and the succeeding July Crisis led to the outbreak of World War I, he became the commander of the Balkanstreitkräfte (Balkan Armed Forces).