Costas Valsamis was born in 1908 on the island of Symi.

From 1932 to 1937 he studied sculpture at the School of Fine Arts, Athens, under Costas Dimitriades. Later, on a scholarship from the French Government, he continued his studies in the French capital firstly at the Ecole des Beaux-Arts in the workshop of M. Gimond and later at the Academie de la Grande Chaumiere with O. Zadkine. Upon completion of his studies, Valsamis settled permanently in Paris.

His primary subject matter is the human figure. Influenced from the trends of the period he arrived at a personal style characterised by simplified forms of expressionistic thrust, sculpting works in gypsum, stone, and bronze.

Valsamis exhibited his work internationally in numerous group and solo exhibitions, notably: the 1948 International Exhibition at the Victoria and Albert Museum, the 1949, 1950, 1951, 1953, 1954, 1955, 1956, 1957, 1958, 1959, 1960, 1961 and 1962 Salon de la Jeune Sculpture, Musee Rodin Paris, the 1953 ‘Sept Sculpteurs Grecs' Petit Palais Paris, the 1967, 1969, 1971 and 1973 Antwerp Biennale, the 1957, 1959, 1961, 1963 and 1965 Biennale du Petit Bronze, Padua, the 1962 Exposition Internationale du Petite Bronze, Musee d’Art Moderne Paris and the 1972 and 1974 Exposition Internationale de la ‘Forme Humaine’ Musee Rodin Paris. 

In 1977, the National Gallery in Athens organised a major retrospective of his work, while in 1980 the French Ministry of Culture honoured him with the order of ‘Knight of Fine Arts'.

His work is found in the National Gallery of Greece, the Municipal Gallery of Athens, the Municipal Art Gallery of Rhodes, the Musee d’Art Moderne, Paris, the Cite Universitaire, Paris, the Casa del Greco, Toledo, the Galleria d’Arte Moderna, Rome, the Museum of Modern Art, Israel, and many other public and private collections.