After dropping out of his study of biology and then of art in his native city of Basel, he trained for an apprenticeship as a house painter. After earning a scholarship, he went to France where he painted rubbish tips, cemeteries and decomposing bodies of animals.
In 1958, he decided to live, in the heart of the slum area of Bezons, in an old bus without wheels. There, in some extremely difficult conditions, he made the portrait of this cour des miracles filled with his friends and models, the migrants and the gypsies. Familiar with the waste grounds and slums in this area, he kept on painting from nature in his "caravan-studio" some social outcasts, prostitutes, vagrants and disabled people for a decade.
From the 1970s, Jürg Kreienbühl took up again the practice of etching and lithography. Facilitated by the possibility of printing in his studio of Cormeilles-en-Parisis, his important and continuous production accompanied, in addition to portraits and still lives, all the subjects of the following years: a former factory of unsold saints for churches (1975), the pollution and the "France" liner at the "quay of oblivion" in Le Havre (1978-1979), the cemetery of Neuilly-sur-Seine and the building site of La Défense (1980), the abandoned treasures of the gallery of paleontology - closed at that time - in the Jardin des plantes in Paris (1982-1985), the nuclear power station in Gravelines and the port of Dunkirk (1995-1997) and the Swiss subjects in the 1990s (The Warteck brewery, Tribute to Basel, the enchanted garden of artist Bernhard Luginbühl, the mountain landscapes).
Expressed at his beginning through an expressionist manner, his fascination for rot and destruction found a definite form in an objective realism, establishing an uncompromising picture of the socio-economic and environmental disruption in the second half of the 20th century. With the accuracy and hallucinatory sharpness of a scientist, Jürg Kreienbühl made himself the disillusioned painter of the old beliefs, the suburbs and the condemned worlds, the social outcasts and the ravages from urbanization and industrialization.
During the artist's lifetime, he has been exhibited and purchased by major public and private institutions (Kunstmuseum Basel, Aargauer Kunsthaus, FRAC Ile-de-France, UBS AG collection, Migros Museum…). After his death, his work is being progressively rediscovered and reassessed, as shown by its entry in the collection of the Centre Pompidou and the Musée des Beaux-Arts in Rennes.
He is the father of painter Stéphane Belzère.