In 1973 he joined the selection of Belgian artists in the XXVth São Paulo Biennale, where he was granted the Grand Prize in Painting.

Over the years his work concentrated on different techniques, including watercolor, etching, silkscreen, illustrations, mosaics, and stained glass, which showed the diversity of his art.

His work Ein Baum stirbt - Un albero muore, 1974, is by Museo Cantonale d’Arte [de] of Lugano.

In 2005 the city of Florence held a grand retrospective of his work at the Palazzo Vecchio and the Forte di Belvedere.

Folon published his drawings in newspapers, mostly in the US, where he was recognized earlier than in Europe and illustrated books by Franz Kafka, Ray Bradbury, Jorge Luis Borges, Guillaume Apollinaire, Jacques Prévert, Boris Vian, Guy de Maupassant, Albert Camus, Herbert George Wells, Jean de La Fontaine and Romain Gary, under the name of Émile Ajar.

Folon made murals (Magic City for the Brussels subway, 1974; Waterloo Station for the London tube, 1975), posters for theater and opera (Spoleto Festival, 1978; Teatro Olimpicio, 1987) and cinema (The Purple Rose of Cairo, by Woody Allen, 1985; La spirale, by Armand Mattelart and Chris Marker, 1976), theater and opera scenery (Geneva and Brussels, 1981; Venice and Roma, 1989), short films for TV (Italiques TV show, by Marc Gilbert (in French), on the soundtrack of Gott mit uns composed by Ennio Morricone, 1971-1974, opening and closing sections for the French channel Antenne 2, 1975–1984), wooden sculptures, logotypes (Éditions Larousse, Bicentenary of the French Revolution, 1989; Philexfrance, 1989), tapestries (Congress Hall of Monaco, 1989), ships (1990), logos (bird emblem for the Tignes-Albertville Paralympic Winter Games, 1992), church windows (1992), sculptures (La mer, ce grand sculpteur, Knokke, 1997), and even a Palio flag (Siena, 1999).

Folon writes in a brief afterword: "We build in our dreams a monument to the unknown postmen to thank them all for having allowed these images to reach their destination.

In 1980, the disco singer Sheila mentions him in 'Les sommets blancs de Wolfgang,' on her album Pilote sur les ondes.

[8] In 2015, Cyril Houplain (in French) mentions Folon as an inspiration to create the visual universe of -M- aka Matthieu Chedid's album Nous deux (Ma mélodie).