Having lost his father, he took his mother’s name instead of the paternal Apostolellis. He studied at the Cydonia high school. In 1913 he entered the third year of the Athens School of Fine Arts, but two years later he interrupted his studies and, after travelling in various countries, settled in Paris till 1919, where he wrote the book Pedro Cazas. He returned to his homeland and taught French and artistic subjects at the high school. After the Asia Minor Disaster he went to Lesbos as a refugee and then Athens and worked on the Εγκυκλοπαιδικόν Λεξικόν Ελευθερουδάκη (Eleftheroudakis Encyclopaedic Dictionary). In 1923 he travelled to Mt. Athos and came into contact with Byzantine painting. The same year he had an exhibition with Konstantinos Maleas and showed his works at the Girls’ Lycee of Athens. He worked as a preservationist at the Byzantine Museum of Athens (1930), the Coptic Museum of Cairo (1933) and the Corfu Museum (1934-1935) while starting in 1936 he worked on the preservation and cleaning of the wall paintings of the Perivleptos church in Mystras. In 1932, assisted by Yannis Tsarouchis and Nikos Engonopoulos, he painted frescoes in his house, which are today in the National Gallery, and in 1933 got his diploma from the School of Fine Arts. He participated in Panhellenies Exhibitions (1938, 1948, 1957) the Venice Biennale of 1934 and the 2nd Biennale of Alexandria (1957). From 1937 to 1939 he did the wall paintings for the City Hall of Athens, employing a Byzantine style. In 1960 he was awarded the prize of the Athens Academy for his two volume Έκφρασις, ήγουν ιστόρησις της παντίμου ορθοδόξου αγιογραφίας (Expression, that is, the History of All-Honorable Orthodox Iconography), published by Astir, as well as being presented with the Order of the Phoenix, while in 1965 he received the Prize of Arts and Letters of the Athens Academy. He painted many churches, among them Kapnikarea in Athens (1942-1953), as well as a large number of portable icons, and was also involved with the illustration and writing of books. Retrospective exhibitions of his work have been organized at the National Gallery (1978), the Cultural Center of the Municipality of Athens (1983), and the Macedonian Center of Contemporary Art (1986). Employing Byzantine and folk painting as the guiding forces of his painting, as well as studying the creations of older periods, such as the portraits of Fayum, he proved with his work to be a firm supporter of the demand for the authenticity of Greek expression, while his contribution to the fashioning of modern ecclesiastical painting is considered definitive.