Günther was born in Varnsdorf, Bohemia (in the present-day Czech Republic). Her debut was in 1897 in Hermannstadt, now Sibiu, in Romania. She achieved stardom in Vienna in 1901 as O Mimosa San in The Geisha. She subsequently sang in England, France and Russia.
She created the title roles of Franz Lehár's The Merry Widow in 1905 and Leo Fall's Die Dollarprinzessin (1907), also appearing in the premieres of Fall's Die fidele Bauer (1908) and Emmerich Kálmán's Der kleine König (1912). She died in Vienna, Austria.
From 1903 to 1911, Günther recorded ten 78 rpm sides of music from The Merry Widow, Heinrich Reinhardt's Der liebe Schatz, Leo Ascher's Vergeltsgott and Franz Lehár's Eva, which have been reissued by Truesound Transfers (TT-2111).
- Steane, J B (1992), 'Günther, Mizzi' in The New Grove Dictionary of Opera, ed. Stanley Sadie (London) ISBN 0-333-73432-7