[1] Born at Hrafnseyri, in Arnarfjörður in the Westfjords area of Iceland, he was the son of Þórdís Jónsdóttir and pastor Sigurður Jónsson.

[2] After completing his education, Jón began to work at the Arnamagnæan Institute, which was then the home of the manuscripts of the Icelandic sagas.

[4] Jón's way of communicating with the Icelandic nation from Denmark where he lived and worked was to publish an annual magazine called Ný félagsrit (New Association Writings).

[5][6] Historian Gunnar Karlsson describes him in the following fashion, Jon Sigurdsson was by no means a typical 19th-century national hero.

Above all, he was a protagonist of modernization, democracy, human rights and economic progress... Jon's career was not typical for a leader of a liberation movement either.

On the contrary, for most of his life he was sustained by rather generous research grants from various scholarly institutions, more or less funded by the Danish treasury.

He also served as the President of the Copenhagen Department of Hið íslenska bókmenntafélag (the Icelandic Literature Society).

[citation needed] The apartment which Jón and Ingibjörg rented at Øster Voldgade 12 in Copenhagen from 1852 is called Jónshús and has been the property of the Icelandic government since 1967.