He had a famous younger brother Lujo Vojnović, who would later play an important political and cultural role in the late 19th- and 20th-century Dalmatia and Montenegro.

[1] At this time, Vojnović's pro-Serbian ideas were apparent from his work, in which he enthusiastically supported the unification of South Slavs under Serbia.

[1] Because of his claims of being a nobleman, and because of his unrestrained Yugoslavism, by 1924 Miroslav Krleža had engaged in a public feud with him, calling him a fake count and a drama dilettante.

[2][3] In 1928, Vojnović's eye problems became acute, threatened with blindness, and in ill health, he went to Serbia to be treated in a sanatorium in Krunska street, Vračar, Belgrade.

[7][8] Vojnović was the author of dramas of naturalistic cut, inspired by the literary and patriotic traditions of the Republic of Dubrovnik.

He is the author of psychological dramas such as: Lady of the Sunflower (1912; filmed in 1918 by Michael Curtiz), and of pieces such as: Dance of Masks in the Attic (1922), which reflect the influence of Luigi Pirandello on Vojnović.

His brother Lujo Vojnović had actively taken part in the Serb Catholic movement in 19th century Dubrovnik, unlike Ivo.

[12] In 2010, the National and University Library in Zagreb and the Dubrovnik branch of Matica hrvatska published the combined letters of Ivo Vojnović, in three volumes, collected by Tihomil Maštrović and edited by Luko Paljetak.