He was born in Piraeus in 1912 and spent his childhood in Larnaca, Cyprus, birthplace of his father. He maintained close relations with Cyprus, throughout his life. He studied Law and Political Science at the Athens University and worked at the Diplomatic Service of the Ministry of Foreign Affairs from 1946 to 1958. He painted and actively participated in the greek cultural life, without actual painting studies. He was a founding member of the art group Armos through which he started exhibiting his work in 1948. His familiarization with the modern art movements of the time, became more intense from 1950 to 1952, when he lived in Paris as a Secretary of the Greek Consulate. His first solo exhibition was held in Athens (Ilissos, 1954).
After retiring from the diplomatic corps, he was elected professor at the Athens School of Fine Arts in 1959, where he served as Director (1975-77) and Dean (1977-78). He taught at ASFA until 1982.
Although his painting appears to have certain common features with the art of his generation, it stands out for the bold use of colour and the freedom of his forms. The direct impression of visual stimuli on the canvas, being combined with expressionist tensions, highlights the psychological dimension of his works and their particularly painterly quality. What mostly characterizes his personal idiom is the shaping of the form with vigorous, dynamic brushstrokes, which often have a distorting effect, without dissolving, however, the structure of the image. He has painted landscapes, still lifes and portraits of many friends and personalities, but his preferred subjects are female figures and nudes.
He was also involved in stage design and clay sculpture. He published works of literature in magazines, a collection of short stories (1947) and five collections of poems (1989, 1990, 1993, 1995 and 2003).
He exhibited his work in solo and group exhibitions in Greece, Cyprus, many European cities and New York. He participated in the 3rd and 4th Biennale of Sao Paulo (1955 and 1957, with honorable mention), and in the Biennales of Alexandria (1961) and Venice (1966). In 1986 he presented his first retrospective exhibition at the Athens National Art Gallery. In 1995 he received the Excellence in the Arts and Letters Award by Cyprus and the Athens Academy Award of Excellence in the Fine Arts. Seven years after his death (Athens, 2003) his last retrospective exhibition was presented at the B & M Theocharakis Foundation in Athens, entitled Yorgos Mavroidis: Anthropocentric painting, 1947-2003.