Having married Albert Meeùs, a Belgian magistrate in 1942, she became involved with him in the Catholic movement of the Teams of Our Lady, for which they became responsible in Belgium but resigned in the early 1960s.
She won the Victor-Rossel Prize in 1967 for her second novel, L'Odeur du père, an excerpt of which was published in Les Temps Modernes by Simone de Beauvoir, with whom she maintained an ongoing correspondence.
In the story Célébration des grands-mères, published in 1969, she retraces her childhood tossed around between her paternal (petty aristocracy in Ghent) and maternal (upper bourgeoisie of Liège) families who took charge of her alternately with her younger brother and sister.
Becoming a journalist, she shared with Françoise Collin the responsibility of the cultural pages of the weekly La Relève (1965-1970), where they created in 1970 a "Women" section.
Marie Denis also produces articles for La Revue Nouvelle, Le Ligueur (newspaper of the Ligue des Familles in Belgium), etc.