Her personality drew the attention of Edwige Feuillère, who she then acted alongside in L'Aigle à deux têtes by Jean Cocteau.

Alongside Gérard Philipe, she played Chimène in Le Cid, performed at Chaillot, and subsequently went on tour across Europe (1954).

In 1948, she played the role of Édith de Berg in the cinematic adaptation of L'Aigle à deux têtes by Cocteau with Feuillère and Jean Marais.

Varda recalls Monfort's participation in the film: "Curious and a pioneer by nature, she threw herself into the project with delight and discipline.

"[5] Separated from Maurice Clavel, Silvia Monfort shared her life with the director Jean-Paul Le Chanois and participated in his films.

Despite having an arm in a plaster cast, Le Chanois insisted that she play a Polish prisoner alongside François Périer and Pierre Fresnay in Les Évadés (1955), a film inspired by a true story.

During the 1960s, Silvia Monfort was passionate about cultural decentralization and, thus, set out on the road with Jean Danet and his Tréteaux de France, a travelling theater group.

On 23 June 1965, Silvia wrote to Pierre Gruneberg: "I've convinced Danet to schedule for September a series of performances of the Prostitute and of Suddenly, Last Summer under a big top around Paris (in this way the inconvenient returning directors will be able to come see it there if they need to).

In the collection of this correspondence, Letters to Pierre,[7] Danielle Netter, assistant director, adds: "The Tréteaux de France was an extraordinary theatrical tool that gave us the occasion to present Sophocles and other dramatic poets before the tenants of the HLM, and one evening to hear a spectator declare at the end of Electra to Silvia 'It's as beautiful as a Western!

Monfort explored ancient and modern theatrical repertoires for nearly half a century, whether with the Tréteaux, in festivals, in private theatres, and later in her Carrés.

She was directed by Roger Planchon at Villeurbanne in 1959 in Love's Second Surprise and by Luchino Visconti in Paris in 1961 in 'Tis Pity She's a Whore beside Alain Delon and Romy Schneider.

At Carré Thorigny, she brought about the debut of Bernard Giraudeau in Tom Eyen's Why Doesn't Anna's Dress Want to Come off (1974).

She portrayed Lucrezia Borgia in Victor Hugo (1975), Marguerite de Bourgogne in The Tower of Nesle by Alexandre Dumas, père (1986), Alarica in The Evil Is Spreading (1963), Maid in Jacques Audiberti (1971), Ethel in The Rosenbergs Should Not Die (1968) by Alain Decaux.

I was wildly in love with Alarica from The Evil Is Spreading, Éponine from Les Misérables and recently The Maid by Audiberti.

A study by the CNRS about the great tragediennes who have incarnated this character in the 20th century was published in Pour la Science, the French version of Scientific American.

[8] This study analyzed the relationship between the pauses and the versified text as well as the fluctuations in delivery and demonstrated that Silvia Monfort made the most important use of them (92% of pauses and 3.8 syllables/minute) in relation to other tragic actresses (Sarah Bernhardt, Marie Bell, Nada Strancar and Natacha Amal); this characteristic of her acting contributed to Silvia Monfort's performances being received with an exceptional quality of psychological depth and emotion.

We have hardly grasped the image in the mirror when she dims, and the imminence of this obliteration sharpens the acuteness of the reflection […] What matters is that there has been a meeting in mystery even from the first reading.

The public's fancy led Monfort and Gruss to set up (in 1974) the first circus and mime school in France, L'école au Carré.

At the Carré Thorigny, Alain Decaux awarded Monfort the Legion of Honor in 1973, paying homage to "her passion for the theatre and the inflexible will with which she serves it."

The Nouveau Carré (officially the Centre d'Action Culturelle de Paris) — or "Paris Cultural Center" — eventually encompassed the main theatre, two smaller houses for music and more intimate shows, the circus, a circus school, and a mime school.