Borromeo’s published works, mainly in Latin and numbering over 100, exhibit his interest in ecclesiastical archaeology, sacred painting, and collecting.

In 1623, he reacquired the feudal rights over what has historically been known as the “State” of the Borromeo within the Duchy of Milan, becoming the Marquess of Angera and Count of Arona, titles still used by the family as a courtesy.

The family was influential in both the secular and ecclesiastical spheres and Federico was cousin of Saint Charles Borromeo, the latter previous Archbishop of Milan and a leading figure during the Counter-Reformation.

Following the death of his cousin Charles, he was sent to Rome for higher studies, where he was strongly influenced by Philip Neri, Joseph Calasanz, Caesar Baronius and Robert Bellarmine.

[8] He followed the example of his elder cousin in promoting the discipline of the clergy, founding churches and colleges at his own expense, and applying everywhere the reformed principles set by the Council of Trent.

Among the first were the painter Giovanni Battista Crespi, called Cerano, the sculptor Andrea Biffi and the architects Carlo Buzzi and Fabio Mangone.

The Pinacoteca Ambrosiana is one of the most famous art collections in Italy, including masterpieces such as Leonardo's Portrait of a Musician, Caravaggio's Basket of Fruit, Raphael's preparatory cartoon for The School of Athens, Titian's Adoration of the Magi, the Madonna del Padiglione by Botticelli and numerous examples of the famous vases of flowers painted by Jan Brueghel, Borromeo's lifelong friend.

Antonio Olgiati, the Cardinal's librarian and first Prefect of the Ambrosiana, was sent in search of Latin manuscripts to purchase in south Germany, the Southern Netherlands and France.

A patron of the arts, Federico had the famous Colossus of St. Charles Borromeo erected in Arona,[16] supported the development of the Sacro Monte of Varese (today a World Heritage Site), and participated in the embellishment of the Duomo di Milano where he is buried.

Besides the classics, the Church Fathers and humanist authors, he quotes from contemporary travel-books, and discusses a wide variety of topics, from Egyptian hieroglyphs to the customs and beliefs of the Africans of Guinea and the origin and antiquity of writing.

[15] The Ambrosiana contains the copy of The Assayer, 1623, which Galileo presented with a covering letter to the Cardinal, 'not because I think it worthy to be read by you, but for my own esteem and to procure life and reputation for the work, in itself low and frail, in your most Illustrious and Reverend Lordship's heroic and immortal library.

On one side of the pedestal of the statue is the phrase from Manzoni's I Promessi Sposi: "He was one of those men rare in every age, who employed extraordinary intelligence, the resources of an opulent condition, the advantages of privileged stations, and an unflinching will in the search and practice of higher and better things".

While at the service of Federico Borromeo, Aquilino Coppini published in 1607 his book of sacred madrigals with contrafacta texts prepared by him, based on works by Claudio Monteverdi and others.

[22] The effort to canonize Federico began soon after his death, and documents in support of his case were still being collected in the 1690s, but the process was never institutionalized by Church authorities due to the opposition of the Spanish crown.