Having participated in the Velebit uprising in 1932, he joined the Royal Italian Army and returned to Croatia following the Axis invasion of Yugoslavia in April 1941.

[2][3] He served as an officer in the Royal Yugoslav Army prior to joining Ustaše units based in Italy in the summer of 1932.

At the beginning of December 1937, Italian authorities arrested him and other members of the Ustaše on suspicion that they were planning to assassinate Yugoslav Prime Minister Milan Stojadinović.

[7] On 3 July 1941 Boban commanded one of three main groups of Ustaše forces that attacked the rebels along the line: Vranjkuk - Rupari - Trusina - Šušnjatica.

[10] Boban was promoted to the rank of general in December 1944 and became the head of the Podravina-based Fifth Ustaše Active Brigade of the Croatian Armed Forces that month.

In May, he withdrew with the Ustaše towards Austria and is reported to have successfully reached the town of Bleiburg,[1] alongside Pavelić and Vjekoslav Luburić.

[15] In July 2022, twenty-five of the Mostar city council's thirty-five members voted to remove street names named after figures linked to the World War II fascist and genocidal Ustaše movement, among them Boban, Mile Budak, Mladen Lorković, Ante Vokić, Đuro Spužević, Jure Francetić and Ivo Zelenek.