From the bare rock of the glacial era it resurfaced in history in the year 846 as an islet with a few houses, a small church dedicated to San Vittore, a cemetery and some olive plants used in the liturgies. During the medieval age, the Island of San Vittore belonged to various owners (abbots and bishops) and it was only in 1501 that the document appeared that ratified the passage of ownership from the Bishop of Novara to the noble Lancillotto Borromeo.
Through marriage, the Island of San Vittore was transferred in 1520 to the Trivulzio family, and it was only in 1563 that Renato Borromeo regained possession of the property, to which he gave the name Isola Renata. New impetus was given to the construction of the Palazzo by calling on Pellegrino Pellegrini, known as Il Tibaldi, a key figure in Lombard culture and the trusted architect of Carlo Borromeo, Archbishop of Milan. The late 16th-century appearance of the Palace that we still see today dates back to this period. The gardens progressed significantly thanks to architect Filippo Cagnola, who in 1710 immortalised staircases, pergolas and vases with great precision.
At the end of the 18th century Isola Madre had taken on the appearance that is substantially conserved today, and it began to be considered a place of peace and repose thanks to its mild climate and luxuriant nature. Subsequently the greenhouses (1826) and the family chapel were built, the latter at the wishes of Vitaliano IX starting from 1858 by architect Defendente Vannini.
In the early 20th century came the idea first of transforming Isola Madre into a hotel, and then of renting it out privately to a very select clientele. But it was Giberto and Bona Borromeo Arese who defined the future of Isola Madre between the 1960s and 1980s: the Palazzo (sumptuously furnished with furniture and works of art coming from Villa Borromeo Arese in Cesano Maderno) and the vast gardens were made available definitively for the enjoyment of the public.