Since returning to Switzerland in 1987, he has started to work as a freelance documentary photographer and photojournalist working in color and black & white and has visited all five continents, with a preference for Africa. He was a member of the Network Photographers Agency in London from 1991 to 1997 and a founding member of Pixsil from 2002 to 2009. He is now working as a freelancer photographer .
He is currently represented by the photo agencies Luz Photo and Redux Pictures.
He has worked with Médecins Sans Frontières, the Global Fund, the World Council of Churches, Heks (Interchurch Aid), the Swiss Red Cross and the Syngenta Foundation.
Ruef’s photographs have been published in major international magazines and newspapers, such as Time, The Observer Magazine, The Independent Magazine, Daily Telegraph, The Economist, Le Monde, Libération, L’Express, Le Nouvel Observateur, L’Hebdo, El Pais Semanal, Geo (South Korea), Rhythms Monthly (Taiwan), Discovery (Honk Kong), Ogonyok, Marie Claire (Italy), D La Republica, Der Spiegel, Die Zeit, Das Magazin, Neue Zürcher Zeitung.
He had solo exhibitions in Switzerland in the Musée de l’Elysée in Lausanne, the Fotomuseum in Winterthur, the Völkerkundemuseum in Zurich, the Museo d’arte Mendrisio. His work has also been shown at the Museo da Imagem e do Som – MIS – in São Paulo, the Centro Culturale Svizzero in Milan, the Bibliothèque Municipale in Bordeaux, the Substation in Singapore, the Jordan National Gallery of Fine Arts in Amman, the Leica Gallery Zingst, Germany and the Leica Gallery in Salzburg, Austria.
Among others, he had collective exhibitions in China, 10th Shanghai International Photographic Art Exhibition; in Tirana, Albania for Objective: People’s World ; in Culturgest Lisboa, Portugal for O seculo do corpo. Trabalhos fotograficos 1990-1999; in Fotomuseum Winterthur in Switzerland for Weltenblicke. Reportagefotografie und ihre Medien.
Didier Ruef has published seven books: in 1998 Paysans de nos montagnes | Editions Monographic and in German translations as Bauern am Berg | Offizin Verlag and in Italian as Vita di montagna | Edizioni Casagrande; in 2005 Afrique Noire | Infolio Editions; in 2007 Enfants Prisonniers | DiDé; in 2011 Recycle | Labor et Fides in French and English and Recycle | Edizioni Casagrande in Italian and German; in 2012 Bestiarium | QTI in Italian; in 2018 Homo Helveticus | Till Schaap Edition in French, German and English | in 2021 2020 | Till Schaap Edition in French, German, Italian and English