Seidl was born in Vienna as the only son in a family of Swiss origin where the father was a respected
lawyer. He attended university to study philosophy and law but, upon the early death of his father,
he was compelled to seek employment as a private tutor and to gain a teaching degree.
He married the sister of the cellist, Karl Schlesinger, Therese Schlesinger, who bore him two
children. He was subsequently appointed teacher at Celje, Slovenia in 1829.
His high reputation led to his elevation in 1840 to custodian of medals and antiques at the imperial
cabinet in Vienna; and later as censor of books following which, in 1847, to election as member of
the Imperial Academy of Sciences.
He wrote the laudatory Austrian National Anthem after which he received numerous accolades leading
to imperial counsellor in 1866; but ill health claimed his life shortly thereafter.
He was a prolific poet and novelist including some works in lower Austrian dialect. He contributed
frequent articles to several learned journals and he was instrumental in publishing the first poems
of Nikolaus Lenau. Some poems were set to music by Schubert and Loewe.