Nikos Eggonopoulos was born in October 1907 in Athens and completed his basic studies internally at a Lyceum in Paris. In 1927 he served his military service and after his dismissal he worked as a translator at a bank and a clerk at the University, while in 1930 he was appointed to the Ministry of Public Works as a designer in the Directorate of City Plans.
In 1932 he enrolled in the School of Fine Arts, where he studied under Konstantinos Parthenis, while at the same time he attended classes in Byzantine art in the workshop of Fotis Kontoglou and A. Xyggopoulos, together with Giannis Tsarouchis. He studied freely in Paris, Vienna, Munich and Italy. He taught painting, art history and scenography at the School of Architecture of the NTUA since 1938, successively as a curator, part-time, full-time and full-time professor. During the same period he met other important artists, including Andreas Empirikos, Giannis Moralis and Giorgio de Chirico.
Throughout his studies in painting, Eggonopoulos remained in his position at the Ministry and in 1934 he was placed in the Topographic Service, where after six years he was made permanent with the rank of First Class Designer.
The first samples of his painting were presented in 1938 at the Art Exhibition of Modern Greek Tradition and were works depicting old houses of Western Macedonia.