After graduating in graphic design from the Kunstgewerbeschule in Basel, Ballmer moved to Milan where he began to collaborate with the Studio Boggeri. In 1956 he was employed by Adriano Olivetti as a graphic designer at the department of development and advertising in Ivrea. In 1970 he designed the Olivetti logo, which he later redesigned. By founding his own studio Unidesign in 1971, he became self-employed. He worked for major companies enterprises including Weber from the Fiat group, Wertheim department stores in Spain, the graphic firm Nava, the fashion designer Valentino, Pirelli, La Roche and Colmar. From 1977 on he taught at Milan Polytechnic. He has taken part in exhibitions in Venice, London, Paris, Milan and Johannesburg. Ballmer has received several prizes, including a Compasso d’Oro (1954), an award for the best Swiss poster (1961), an award at the Swiss National Exhibition (1964 and 1971), and a gold medal for the Olivetti corporate identity at BIO 5 in Ljubljana (1973).