Otto Sonnleitner was born in Würzburg, where his father already worked as a sculptor. After a sculptor apprenticeship in his father's workshop and while attending the "hands-free, head and nude drawing class" of the "Central Association Polytechnic" (Polytechnischen Zentralvereins) (a facility, where the department 'design' was later created at the advanced technical college in Würzburg), he studied sculpture and graduated as a master student under the tutelage of Joseph Wackerles at the Academy of Fine Arts in Munich.