The patron saint of Mirabello Sannitico is Saint George, celebrated on 23 April in the church dedicated to him.
The earliest reference to the town appears in a church register from February 1193, where abbot Ferulfo mentions the church of San Salvatore di Mirabello, whose site is now unknown, adjacent to the Tappino river: in the following centuries numerous bloody disputes over water rights were fought between Mirabello Sannitico and neighbouring Ferrazzano. The area has historically been struck by several major earthquakes, in 847, 1294, 1309, 1456, 1587, 1688 (with no victims, since the population was in the fields) and 1794; the earthquake of 26 July 1805, which killed hundreds of people across Molise and around three hundred in Mirabello alone, reduced the church of San Nicola, already previously damaged, to rubble.
The municipal coat of arms and banner were granted by decree of the President of the Republic on 28 January 2004.
