Giulianello has very remote origins; the first documented information dates back to 143 B.C., the year it was presumed the town was founded under the rule of the Western Roman Empire. The site, located in a particularly impervious area, was far from the main roads of communication and almost entirely covered by scrubland. The area was mainly populated by semi-nomadic herdsmen who used the large free spaces where grass grew wild without having to plough the ground.
It was only during the late Roman Empire period that people began to show interest in the area and buildings began to appear on that part of the area then called Fundus Julianus, currently Giulianello. Numerous farmhouses and farms were built for hunting and for summer residences.
However it was only in 1020 that a Bull issued by Pope Innocence III made an explicit and unequivocal reference to the presence of a community located at Juliano.
Over the centuries, the town was governed by various noble families, including the Salviati family in the 15th century and the Borghese in the 18th. Later, in 1870, it passed under the control of the Church of Rome.