At the age of 22, she got hired by the Ulmer Theatre, where she performed numerous operas, operettas and musicals in the following six seasons.
In the summers of 2003 and 2004 Iva Mihanovic sucessfully sang the role of „Juliette“ in „The Count of Luxembourg“ and „Ciboletta“ in „A night in Venice“ at the Bad Ischl Lehar Festival. In the summer of 2007 she sang the role of „Pepi“ in „Wiener Blut“ at the Lake Festival Mörbisch directed by oscar-winner Maximilian Schell. This role also led her in recent times to the City Theatre St. Gallen, to the Music Theatre Schönbrunn (Vienna) and to the Theatre of Würzburg.
In 2008 the Castle Festival in Langenlois hired her as „Stasi“ in „The Gipsy Princess“ and later on in the summer of 2010 Iva Mihanovic joined it again as „Ciboletta“ in „A Night in Venice“.
In the summer of 2011 Iva Mihanovic was again the soloist at the Lake Festival in Mörbisch and sang „Arsena“ in „The Gypsy Baron“ directed by Ks. Prof. Brigitte Fassbaender.
After her engagement at the Ulmer Theatre in the last years she always remained as a gueat („Christl“ in „The Bird Trader“ and „Ännchen“ in „Der Freischütz“). Since 2007 she appeared in the role of „Ottilie“ in „Im Weißen Rössl“ at the State Theatre in Wiesbaden, also in the role of „Papagena“ at the State Theatre in Mainz, furthermore in the role as „Valencienne“ in „the Merry Widow“ at the Theatre of Augsburg, in the role of „Annina“ in „A Night in Venice“ at the Theatre of Trier and in the role of „Christl“ in „The Bird Trader“ at the theatre of Lucerne.
In the winter of 2009 she performed at the City Theatre in Baden as „Dolly Marbanks“ in Granichstädten’s operetta „The Orlov“.
From 2009 to 2011 she was a member of the ensemble of the Opera in Leipzig (Musical Comedy) and sang among many other roles „Marie“ in „Zar and Zimmermann“, „Hedi“ in „Two Hearts in three-quarter time“, „Mi“ in „The Land of Smiles“ and „Miss Mabel Gibson“ in „ The Circus Princess“.
In the seasons of 2011/2012 and 2012/2013 she made another guest appearance at the State Theatre in Wiesbaden, however this time in the role of „Briefchristl“ in Zeller’s „The Bird Trader“.
In May and June of 2012 she performed „Flower Girl“ in Richard Wagner’s „Parsifal“ at the Richard Wagner Festival in Wels and later on in 2013 „Sheperd“ in „Tannhauser“.
She sang in the season of 2012/2013 „Ottilie“ in „Im Weißen Rössl“ in the opening premiere of the new directionship at the State Theatre on Gaertnerplatz in Munich.