Šimunić played with HŠK Građanski Zagreb in the Yugoslav First League as a goalkeeper from 1936 until 1943.

[1] Following his retirement from professional football he was appointed the head coach for NK Maribor in 1961, where he captured the Yugoslav Second League title in the 1966–67 season.

[2] In 1969, he went abroad to manage Grazer AK, and returned to Yugoslavia in 1973 to coach FK Borac Banja Luka.

In 1972, he went to Canada to manage the National Soccer League side Toronto Croatia.

[3] In June 1974, he returned to manage Toronto Croatia and won the NSL Championship.