He specialises in the art of Mondrian and De Stijl and the early avant-garde of the 1920s. He has published works on Mondrian, De Stijl, Georges Vantongerloo, Gerhard Richter, Situationism and Bioart. He has curated numerous exhibitions in Europe and the United States. He has worked on such expositions as Für eine neue Welt. Georges Vantongerloo 1886-1965 und seine Kreise von Mondrian bis Bill (Stiftung Wilhelm Lehmbruck Museum, Duisburg, Gemeentemuseum, Den Haag, 2009-2010), De Stijl (Centre Georges Pompidou, Paris 2010) and Mondrian and his Studios (Tate Liverpool, 2014) ). In 2016, Marek Wieczorek co-organised the international symposium De Stijl and its Legacy at 100 dedicated to the De Stijl movement at the Rijksmuseum in Amsterdam.