Szemere was born in Vatta into a poor noble family, which traditionally descended from the lineage of 9th-century chieftain Huba.

In 1835 Szemere travelled around the world and visited amongst other places Berlin, Amsterdam, Dublin, Lausanne, Paris and London.

From 1848 Szemere was responsible for Upper-Hungary as a politician, therefore he was at Miskolc to reorganize the Upper-Tisza Legion, which had retreated after Franz Schlik's attack.

From 2 May 1849 Szemere was Home Secretary and Prime Minister alongside Regent Lajos Kossuth, until his resignation.

On 29 July 1849 they accepted the national act which provided free language use for ethnic groups in local administration and education.

After the Hungarian surrender at Világos Szemere buried the Holy Crown of Hungary, the Sceptre, the orb and other regalia on 23 August 1849 at Orsova.

In 1869 Szemere died and his ashes were interred in Buda, but on 1 May 1871 they were disinterred and moved to a church in the Avas district of Miskolc.