Rallis Kopsidis was born on the island of Limnos.

In 1949 he enrolled at the School of Fine Art, Athens. However, he abandoned his studies in the fourth year and continued studying under Fotis Kontoglou, between 1953 and 1959 with who he later collaborated in executing church frescos.

Kopsidis' initial work drew its influence from his teacher Fotis Kontoglou. Up to 1975, influences from Byzantine, post-Byzantine, and folk-art are predominant in his work. During this period, he developed a naïve painting language, anthropocentric, his subject matter being the working-class people and their customs.

After 1975, his subject matter and painting technique changed direction developing a more free personal style. Using austerity, stylization, miniature rendering of detail and a restrained colour scale (with a preference for earthy tones), Kopsidis depicted landscapes of Lavrio with its industrial remains. The themes often included images of poverty, loneliness, and abandonment, but also views of the castle of Limnos where the central figure is a youngster in a boat, reminiscent of his childhood.

From the early 1980s, his work focused on landscapes incorporating the human figure. Children, adolescents and aged figures, nudes, women in period clothing, figures reminiscent of hagiographies and period photographs are placed in barren landscapes, deserted beaches, castle ruins, piles of rubble or rubbish with colourful flowers that grow among them.

Additionally, he worked on many church fresco commissions in Greece and abroad, such as the Monastery of Chevetrogne in Belgium and the church of the Orthodox Center of the Ecumenical Patriarchate in Chambesy, Geneva.

Kopsidis’ literary work is equally important. He has written, illustrated and engraved many books such as ‘Σταυροί στην Αθήνα’ (1963); ‘Προσκυνητάρι της Αίγινας’ (1965) and ‘15 Ξυλογραφίες για το Άγιον Όρος’ (1968). ‘Κάστρο ηλιόκαστρο’ (1980) and ‘Το τετράδιο του γυρισμού’ (1987) are based on his childhood memories of the 1930s and 1940s from his birthplace, the island of Limnos.

In 1989 the National Gallery of Greece staged a large-scale retrospective of his work.

His work can be found in many public and private collections in Greece and abroad, notably at: The National Gallery of Greece, the Athens Municipality Collection, the Thessaloniki Municipality Collection, the Teloglion Fine Arts Foundation and the National Bank of Greece Cultural Foundation.