Karel Appel was born on April 25, 1921, in Amsterdam. From 1940 to 1943 he studied at the Rijksakademie van Beeldende Kunsten in Amsterdam. In 1946 his first solo show was held at Het Beerenhuis in Groningen, the Netherlands, and he participated in the Jonge Schilders exhibition at the Stedelijk Museum in Amsterdam. Around this time, Appel was influenced first by Henri Matisse and Pablo Picasso, then by Jean Dubuffet. He was a member of the Nederlandse Experimentele Groep and established the CoBrA movement in 1948 with Constant, Corneille, and others. In 1949 Appel completed a fresco for the cafeteria of Amsterdam's city hall, which created such controversy that it was covered for ten years.

In 1950 the artist moved to Paris, where the writer Hugo Claus introduced him to Michel Tapié, who organized various exhibitions of his work. Appel was given a solo show at the Palais des Beaux-Arts in Brussels in 1953. He received the UNESCO Prize at the Venice Biennale in 1954, and was commissioned to execute a mural for the restaurant of the Stedelijk Museum in 1956. The following year Appel traveled to Mexico and the United States and won a graphics prize at the Ljubljana Biennial in Yugoslavia. He was awarded an International Prize for Painting at the São Paulo Bienal in 1959.

The first major monograph on Appel, written by Claus, was published in 1962. In the late 1960s the artist moved to the Château de Molesmes, near Auxerre, southeast of Paris. Solo exhibitions of his work were held at the Centre National d’Art Contemporain in Paris and the Stedelijk Museum in Amsterdam in 1968, and at the Kunsthalle Basel and the Palais des Beaux-Arts in Brussels in 1969. During the 1950s and 1960s he executed numerous murals for public buildings. A major Appel show opened at the Centraal Museum in Utrecht in 1970, and a retrospective of his work toured Canada and the United States in 1972. Appel, who for many years lived and worked in New York and Florence, died in Zurich, Switzerland, on May 3, 2006.