The early deaths of his mother and eldest brother from tuberculosis, his father's struggles with a mental disease, and the economic ruin of his family marked Ritsos and affected his poetry.

In 1935, he published Pyramids; these two works sought to achieve a fragile balance between faith in the future, founded on the Communist ideal, and personal despair.

Published the same year, it broke with the shape of the Greek traditional popular poetry and expressed in clear and simple language a message of the unity of all people.

He began to explore the conquests of surrealism through the domain of dreams, surprising associations, explosions of images and symbols, a lyricism illustrative of the anguish of the poet, and both tender and bitter souvenirs.

[2] During the Axis occupation of Greece (1941–1945) Ritsos became a member of the EAM (National Liberation Front) and authored several poems for the Greek Resistance.

Today, Ritsos is considered one of the great Greek poets of the twentieth century,[6][7][8] alongside Konstantinos Kavafis, Kostas Kariotakis, Angelos Sikelianos, Giorgos Seferis, and Odysseas Elytis.

Notable works by Ritsos include Pyramids (1935), Epitaphios (1936; second edition, 1956), Vigil (1941–1953), Romiosini (1954) and 18 short songs of the bitter Motherland (18 λιανοτράγουδα της πικρής πατρίδας/18 Lianotragouda Tis Pikris Patridas) (1973).

His best poem is "Romiosini," a lengthy paean to the spirit of the Greek Resistance.Ted Sampson stated that Louis Aragon's declaration about Ritsos was "hyperbolic", but wrote that the poet still "excelled in brief epigrammatic utterances as well as in extended lyrics, sequences, and verse dramas of astonishing imagistic and thematic originality—to say nothing of their latent emotional intensity".