The town is mentioned for the first time in the papal registers of 1332 when it was known as Novum Forum Sicolorum. Evidence shows that is was a craft centre of some size. The town archives contain papers signed by Louis of Anjou, King of Hungary who gave special privileges to the local weavers.

In 1405 King Sigismund of Luxembourg granted the town the right to hold Fairs, and in 1482 King Matei Corvin bestowed the status of the Royal town of Tg -Mures on the town.

On the 29th of April 1616, Gabriel Bethlem, Prince of Transylvania decreed that the town become a free Royal City and changed its name from Székelyvásárhely to Marosvásárhely (Târgu Mures).

For centuries the city was the residence of the "chair" of Mures, an administrative body typical of those set up in medieval times in Transylvania. Over the centuries many Diets of the Principality of Transylvania were held here and the election of princes took place here, as well.

In 1571, opposed to Prince János Zsigmond's intention to restrict the freedom of religion, the Diet of Tg -Mures decided to pass a code assuring the freedom of religious practice for four religious groups in Transylvania: Roman Catholics, Calvinists, Lutherans and Unitarians. At that time the Orthodox church did not have the same status as these four.

In 1754 the "Royal Table"- the supreme Law Court of Transylvania -was moved to Tg -Mures; Alexandru Papiu Ilarian and György Aranka were among the members of this important body.