Following his training at the Royal Academy of Fine Arts in Antwerp, Joostens experimented with different artistic styles and held his first exhibition in 1917. He founded the group Bond zonder Gezegeld Papier (Bond without sealed paper) with Van Ostaijen and the Jespers brothers, and soon discovered Cubism. In 1920 he collaborated with Jos Léonard and the Jespers brothers on Novy, an organisation dedicated to applied arts. He travelled to Paris in 1924 and, two years later, turned towards a Neo-Gothic style. In 1937 he created his first series of photomontages. After World War II, he produced the Poezeloezen series. He died in Antwerp in 1960.