Strossmayer was born in Osijek in the Kingdom of Slavonia, then part of the Austrian Empire, to a Croatian family.

Strossmayer finished school at a gymnasium in Osijek, and then graduated theology at the Catholic seminary in Đakovo.

After Strossmayer's criticism, Imperial government made concessions regarding the official use of the Croatian language in Croatia and Slavonia.

Imperial court disregarded this Croatian decision and negotiated Austro-Hungarian Compromise in 1867, whereby Croatia became part of Transleithania (Hungary).

[6] In 1868, Croatian and Hungarian member of the Diet of Hungary agreed on the Croatian–Hungarian Settlement, an arrangement Strossmayer opposed.

[2] Strossmayer was instrumental in the founding of the Yugoslav Academy of Sciences and Arts in 1866, as well as the re-establishment of the University of Zagreb in 1874.

[9][10] He initiated the building of the Academy Palace (completed in 1880) and set up The Strossmayer Gallery of Old Masters (1884) in Zagreb.

Since the early days of his episcopate, he was a close friend of Franjo Rački, the most renowned Croatian historian of his time.

Their friendship was well documented in a series of four books containing their letters, compiled by historian Ferdo Šišić.

[13] In 1881, Schulzer (a Hungarian-Croatian army officer and mycologist) published a genus of fungi in the family Helotiaceae as Strossmayeria which was named in Strossmayer's honour.