Casiraghi has been in a relationship with
Beatrice Borromeo since May 2008. She is a member of the prominent Italian aristocratic family the
House of Borromeo. She is the daughter of
Don Carlo Ferdinando
Borromeo, Count of
Arona (born in 1935), and his long-time companion, Countess
Donna Paola Marzotto (born in 1955). She has three older half-sisters from her father's marriage to
German model and former
Miss Germany Marion Sybil Zota: Isabella, married to
Ugo Brachetti Peretti, a manager (oil executive) from a noble family, son of Count
Aldo Maria Brachetti Peretti; Lavinia, married to
John Elkann, the son of
Alain Elkann and
Margherita Agnelli de Pahlen, head of the
Agnelli family and member of the steering committee of the
Bilderberg Conferences; and
Matilde, married to Prince Antonius
zu Fürstenberg. They were married in a
civil ceremony on 25 July 2015 in the gardens of the
Prince's Palace of Monaco. The religious ceremony took place on 1 August 2015 on
Isolino di San Giovanni, one of the
Borromean Islands on
Lake Maggiore, Italy. Pierre and Beatrice's first child, Stefano Ercole Carlo, was born on 28 February 2017. Their second child, Francesco Carlo Albert, was born on 21 May 2018. Their third child and only daughter, Bianca Caroline Marta, was born on 4 October 2025. In February 2012, Casiraghi was briefly hospitalized following a physical altercation at a nightclub in New York's
Meatpacking District. Casiraghi and others, including
Vladimir Restoin Roitfeld, approached the table of businessman
Adam Hock, who was accompanied by models
Natasha Poly,
Anja Rubik and
Valentina Zelyaeva, where words were exchanged and an altercation ensued. Hock, who was later charged on eight counts of misdemeanor assault, alleges that Casiraghi was the aggressor and that he struck Casiraghi and his companions in self-defence. Casiraghi was treated at
New York Presbyterian Hospital for a laceration, bruising, and swelling of his face. ==References==