He moved to Paris in 1920, where, under the influence of surrealist poets and writers, he evolved his mature style. Miró drew on memory, fantasy, and the irrational to create works of art that are visual analogues of surrealist poetry. These dreamlike visions often have a whimsical or humorous quality, containing images of playfully distorted animal forms, twisted organic shapes, and odd geometric constructions. Amorphous amoebic shapes alternate with sharply drawn lines, spots, and curlicues, all positioned with seeming nonchalance.

Miró later produced highly generalized, ethereal works in which his organic forms and figures are reduced to abstracts spots, lines and bursts of colors. Miró also experimented in a wide array of other media, devoting himself to etchings and lithographs for several decades. His ceramic sculptures are also notable, in particular his two large ceramic murals for the UNESCO building in Paris (Wall of the Moon and Wall of the Sun, 1957-59).

It was at the end of the 60's when his final period was marked, which lasted until his death. During this time, Miró concentrated more and more on monumental and public works. He was characterized by the body language and freshness with which he carried out his canvasses, as well as the special attention he paid to material and the stamp he received from informalism. He concentrated his interest on the symbol, not giving too much importance to the representing theme, but to the way the symbol emerged as the piece of work.

In 1976 the Joan Miró Foundation Centre of Contemporary Art Study was officially opened in the city of Barcelona and in 1979, four years before his death, he was named Doctor Honoris Causa by the University of Barcelona. Miró died in Majorca, Spain, on December 25, 1983.