In January 1999, Charlotte gained a stepfather and two stepbrothers, (Prince Ernst of Hanover and Prince Christian of Hanover), when her mother married Ernst August, Prince of Hanover. Six months later, Casiraghi’s half-sister, Princess Alexandra of Hanover, was born at a clinic in Voecklabruck, Austria. Casiraghi is godmother to her sister. The family then moved to the Parisian suburb of Fontainebleau.

From 2001 through 2004, as a member of Marcel Rozier’s Team Marionnaud, Casiraghi participated in a number of Junior and Amateur class show jumping competitions. She was trained successively by both of Rozier’s sons, first Philippe and then Thierry Rozier.

She obtained an “excellent” (in French: très bien, the highest possible) mark on her baccalaureate exam in July 2004. After passing her bac, she enrolled in the hypokhâgne and khâgne course at the Lycée Fénelon, in St-Germain-des-Près, Paris, in the hope of entering the École normale supérieure (Paris). She took the written entrance exam for ENS in June 2006, but failed to make the list of candidates eligible to proceed to the oral exam.

In 2007, Casiraghi earned a License of Philosophy (B.A.) from the University of Paris IV: Paris-Sorbonne; Casiraghi completed two internships, firstly with the publishing house of Robert Laffont in Paris, and then later from October 2007 with the Sunday magazine supplement of The Independent newspaper of London. In 2018, Casiraghi told Clara Le Fort of Billionaire magazine: “I continued studying philosophy while at the Sciences Po Doctoral School.”

Casiraghi is a private citizen, but occasionally attends official functions in Monaco, such as a fundraising gala for AMADE Mondiale and Nelson Mandela’s foundation in September 2007. In 2006, she made her debut appearance at Monaco’s Rose Ball (in French: Bal de la Rose), which also raises money for the Princess Grace Foundation.

In June 2009, Casiraghi, accompanied by her uncle Albert II, Prince of Monaco, appeared on the French television programme Stade 2 to speak about her recent enrollment in the Global Champions Tour. It was her first experience of public speaking and she appeared poised and confident.

Since returning to the show jumping sport in April 2009 (after a four-year hiatus), she continues to train with Thierry Rozier. Casiraghi and the bay gelding named GI Joe (owner: Jan Tops), participated in the 2009 Global Champions Tour in Valencia, Spain, Monte Carlo, Cannes, Estoril, Rio de Janeiro, and Valkenswaard.

Casiraghi is a published writer and magazine editor. Her credits include work for AnOther Magazine (its issue for January 2008) and the Sunday supplement to the British The Independent newspaper in the late months of 2007. She was the editor-at-large for Above magazine in 2009. With two friends, she left that role in order to focus on the founding of the ecological/fashion-related Ever Manifesto.

On 21 September 2009, Casiraghi announced plans to publish 3,000 copies of Ever Manifesto, a free publication on what she considers the fashion industry’s harmful impact on the global environment and to promote sustainability in fashion. Casiraghi revealed that her collaborators with the Loro Piana-funded project are the socialite Alexia Niedzielski and advertising executive Elizabeth von Guttman. She also revealed that the environmentally conscious designer Stella McCartney, as well as her own uncle Prince Albert II, greatly enlightened and influenced her. Specifically, she said: “It’s only recently that I’ve questioned the way that I’ve been consuming. I haven’t been as conscious as I should have been.”

In October 2009, Casiraghi was a guest at the Stella McCartney show in Paris. Sitting in the front row with Dasha Zhukova, Paul McCartney and Gwyneth Paltrow, she told Women’s Wear Daily about Ever Manifesto. Copies of the magazine’s first issue were left on the seats before the show. “We will announce [succeeding issues] on the website soon,” she said.

In 2010, she assumed the role of honorary president of the Global Champions Tour (now the Longines Global Champions Tour) in Monaco; her mother had been honorary president of the event as it existed prior to its inclusion in the Global Champions Tour. Since 1997, by the appointment of her grandfather, Casiraghi has been patron of the Public Safety Division, Maritime and Airport Police of Monaco. In 2009, and again in 2011, she joined her uncle for the presentation of the trophies for the Monaco Grand Prix, a task usually undertaken by her mother. Every year since 2006, she has attended the Rose Ball (Bal de la Rose) to help raise funds for the Princess Grace Foundation.

In December 2011, Casiraghi started dating stand-up comedian and actor Gad Elmaleh. Their son, Raphaël, was born in December 2013. As Raphaël’s parents were not married, he is not included in the line of succession to the Monegasque throne. The couple split in June 2015.

Casiraghi founded Swoon Productions in 2012. In 2015, she joined the board of directors of FXB France, an organization founded by her godmother Albina du Boisrouvray in 1989 to combat AIDS and poverty.

In 2014, Casiraghi bought the rights to the book Our Lady of the Nile, which will be released as a feature film in 2020. Casiraghi is one of the producers of the film.

In 2015, Casiraghi founded Les Rencontres Philosophiques de Monaco (literally, “Philosophical Encounters). Her co-founders include her former teacher in Fontainebleau, the philosopher Robert Maggiori. The others founders are Joseph Cohen and Raphael Zagury-Orly. Her mother is among the many honorary members of the group, which is really a think tank on philosophy. They discuss contemporary issues and new publications in the field of philosophy. The writings and the life of Anne Dufourmantelle made a strong impact on Casiraghi, who wrote in particular about Dufourmantelle’s book Défense du Secret in an article for Libération. Casiraghi and Dufourmantelle, who died in 2017, were friends, sharing, by the admission of Casiraghi herself, a passion for not only philosophy but for horses.

2015 was really the last year that Casiraghi participated in multiple phases of the Longines Global Champions Tour. After that year, she reduced her participation to the Monaco phase only.

Casiraghi wrote the preface for a book published in 2017 by the psychoanalyst Julia Kristeva. The two women also published their letters to each other, reflecting on philosophy.

In March 2018, Casiraghi and Maggiori published their Kindle book, through Éditions du Seuil. The title is Archipel des Passions (Archipelago of the Passions). It is a series of dialogues between the professor and the student about the various passions (i.e. arrogance, joy, cruelty, love) and their affects. It is also “an essay on the passion of thought.” The book is dedicated to her father and the passions explored amount to about forty. It “reads like a treatise of the passions.”

She married film producer Dimitri Rassam, the son of French actress Carole Bouquet, in Monaco’s princely palace on 1 June 2019. In March 2018, several credible media sources reported her engagement to Rassam and it was widely noted that she wore a diamond ring at Monaco’s Rose Ball on 24 March. Casiraghi was visibly pregnant by the summer and the couple chose to postpone a wedding until after the birth of their child. On 23 October 2018, Casiraghi gave birth to a second child, a son named Balthazar, who is 12th in line to Monaco’s princely succession, after his mother. The couple married civilly at the Prince’s Palace of Monaco on 1 June 2019. They celebrated in a reception at nearby hotel Villa La Vigie.

On 29 June 2019, they married religiously at the Abbey of Sainte-Marie de Pierredon, outside Saint-Rémy-de-Provence.