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.

Later on, Sonnleitner took over the studio and workshop of his father. His works are often presented in and around Würzburg. He designed several churches, but has also numerous freestanding sculptures (such as the relief "Vater Main" at Kilian House or Wilhelm Conrad Roentgen's at the former Institute of Physics of the University of Würzburg). From Sonnleitner's hands comes the portrait of Jean Paul in Walhalla near Regensburg.