His mother Elsa Kühne was an opera singer and his father Joseph Klarwein was a Brick Expressionist architect and later with the Bauhaus movement.

In Paris, Mati studied from 1949 to 1951 with Fernand Léger, and attended the art schools École des Beaux-Arts and Académie Julian.

[5] In 1956 he met Kitty Lillaz, and traveled with her around the world, including Tibet, India, Bali, North Africa, Turkey, Europe and the Americas.

At a New York exhibition in 1961, organized by Lillaz for the unveiling of the painting Flight to Egypt[6] Klarwein met Salvador Dalí for the first time, whom he called a spiritual father.

The art and culture magazine Juxtapoz, quoting an unnamed source, wrote that Klarwein was "often considered 'the man literally responsible for every great, legendary record cover you've ever seen—if he didn't do it, he inspired it.

Klarwein's own words illuminate the work: "I projected it as a sort of painted musical comedy movie with a Sanskrit swinging cast of thousands, starring Marilyn Monroe, Anita Ekberg, Ray Charles, Pablo Picasso, Brigitte Bardot, Roland Kirk, Cannonball Adderley, Ahmed Abdul Malik, Wonder Woman, Delacroix's Orphan Girl at the Cemetery, Litri and his bullfighters, Lawrence of Arabia, Socrates, Dalí, Rama, Vishnu, Ganesh, the Zork and a Milky Way of Playmates.

"[13] Klarwein produced comparably striking designs for the covers of two Miles Davis albums, Bitches Brew (1969) and Live-Evil (1971).

The association of his images with these successful and widely admired musicians of the time, made Klarwein's work known outside the circle of lovers of contemporary art.

"[17][18] Klarwein also painted many commissioned portraits, including Robert Graves, Noël Coward, Juliette Binoche, Richard Gere, Michael Douglas and Brigitte Bardot.