Casadesus composed soundtracks for a diverse range of productions, such as Divertimento, with Kellan Lutz, Torrey DeVitto, Ola Rapace, Götz Otto by Keyvan Sheikhalishahi, The Climb, a fiction movie by the American director Bob Swaim, the animated film Babar: King of the Elephants, adapted from the classic French comic by Jean de Brunhof, or the TV series Jesus by Serge Moati.

More recently, he composed the music score for several documentary films, such as La Guerre d'Hollywood, Jack London, une aventure américaine, and the TV series Jusqu'au dernier.

Between 1983 and 1997, he composed no less than 22 musical creations for the stage, mainly for Jean Danet's Les Tréteaux de France theatre company and the Théâtre du Marais of Jacques Mauclair.

In particular, he composed the music for Molière's play, L'Avare, which was awarded a prestigious Molière Award in 1989 for the direction by Mauclair[4] Casadesus was then contacted by the American film director Bob Swaim, who hired him in 1997 to replace the famous composer John Barry and write the soundtrack for his feature film, The Climb, with John Hurt, Gregory Smith and David Strathairn.

[5] In 1998, he composed the very first original soundtrack for Marie et le vin, a book by Claire Huynen published by Éditions du Cherche-Midi.

[6] The following year, Casadesus wrote the soundtrack for the cartoon Babar: King of the Elephants, by Canadian director Raymond Jafelice.

[8] In 2001, he wrote seven hours of music for the restored version of the 1921 film Les Trois Mousquetaires, an adaptation of the great French classic by Alexandre Dumas.

This symphonical suite was published by Cezame Music Agency with the title Movements of Life, and a series of three films about the Marey project was released the following year.

[12] Casadesus entered a new phase of collaborations, with the composition of soundtracks for various documentary films in France, in particular for directors Christian Zerbib (En terre étrangère and Nos ancêtres les Gauloises), Michel Viotte (La guerre d'Hollywood and Jack London, une aventure américaine), and William Karel (Jusqu'au dernier : La destruction des Juifs d'Europe).

Thanks to a solid classic training and an interest in recording techniques and new technologies,[19] Casadesus has developed his own style, mixing acoustic instruments and electronic sound effects.

Since 2008, he has contributed to various albums from Cezame's catalogue (Marines, Seascapes, American Road Book, Paysages avec cordes, Motivation & Inspiration, Historical Heritage, 1914 : La grande guerre, Sense and Sensibility, Inspiring Cinematic Choirs, Western, Scandal & Gossip, Freaky Frolics) Greco Casadesus dedicated 14 years of his life to the stage.

From his friendship with Roger Boutry, conductor of the Symphonic Orchestra of the Republican Guard, appeared in 1984 an opportunity to compose for a TV series on the French gendarmerie.

His meeting with directors such as Bob Swaim, Etienne Perier, Serge Moati, Jérôme Diamant-Berger and others, have expanded his skills in film scoring.