Cosmadopoulos was born in Volos in 1895.

He studied painting at The School of Fine Art in Leipzig, Germany and the Grande Chaumière in Paris.

In 1926 he presented his work for the first time in Greece and abroad. Later in 1936 he was awarded The Silver Medal of The International Exhibition of Paris. He also participated in The Venice Biennale of 1934 and 1936. He presented his work in many national and international shows.

Cosmadopoulos’ themes include portrait, landscape and compositional. His style moves between realism and impressionism. His paintings are made up of small, thin, sharp yet visible brush strokes of colour in a way where realism and poetry merge harmoniously. Emphasis is given on accurate depiction of light in its changing qualities. In some of his works the inclusion of movement is a crucial element of human perception and experience.

His work can be found in The National Gallery of Greece, The Municipal Gallery of Athens, The Municipal Art Gallery of Rhodes, The Leventis Gallery and many other public and private collections.