Recent studies date the first stable settlements back to Roman times: this hypothesis is supported by the etymological origin of the name, which would derive from the name Bellelo.
Already then the territory was dotted with countless urban agglomerations of tiny dimensions, a characteristic that the country has maintained over the centuries. The localities of Brevieno, Ghisalerio and Blello (as well as numerous scattered farmhouses), which make up the municipal territory, are ideologically united by the parish church, dedicated to the Annunciation of Mary. Built during the 18th century on Monte Faggio, and renovated a century later, it features paintings by local painters Quarenghi and Pollazzo.
Over the centuries Blello has always maintained the characteristics of the small mountain village, with a limited number of inhabitants mostly dedicated to living off what nature provided them.
Consequently, the main activities have always been those of the shepherd, the breeder, the woodcutter and the charcoal burner, that is, the one who transformed wood into charcoal.
Few are therefore the historical information of the town that several centuries ago gravitated politically in the orbit of the Imagna Valley: now inserted in the social and economic context of the Brembilla Valley, it depends administratively on the Brembana Valley.
It is known, however, that the small villages that make up Blello were only marginally affected by the faction struggles between Guelphs and Ghibellines during the Middle Ages. Here, in fact, there were no episodes of chronicle, although often people from nearby villages, fleeing persecution from one or the other side, took refuge in these isolated places.
In fact, the inhabitants themselves, like those of the nearby municipality of Gerosa, always tried to keep themselves out of power disputes, which guaranteed them peace of mind, safe from clashes and retaliation both during these struggles and after the advent of the Republic of Venice.
The following centuries did not see any significant events involving the small community, which, strengthened by its isolation, followed the events of the rest of the province without participating directly in them.
From the twentieth century the town began to suffer from a strong emigration of its inhabitants, attracted by greater professional and economic opportunities outside the municipal territory, making Blello the smallest town in the province.
Recently the diversified economic occupation and an improved road system, which allows communication with the Brembilla Valley and the Imagna Valley, allow those who do not want to lose their origins to access the structures of the nearest centres. This has allowed a small development of tourism, suitable for those who want to enjoy the tranquility of nature while admiring the panorama of the entire small valley.