He first studied painting at the School of Arts with Nikiforos Lytras and sculpture with Georgios Vroutos; he went on to S. Eberle’s workshop and the Munich Academy, where he attended composition classes. He visited and studied museums in Florence, Rome and Naples. Returning to Greece in 1900, he established a workshop; in 1910, he had courses at K. Konstantinidis’s workshop. In January 1912, he was appointed professor at the School of Arts and remained in this post throughout his life. His contribution to the preservation of Yannoulis Chalepas’s works was substantial: He visited the island of Tinos in 1922, leading a Ministry of Education team, in order to cast in plaster the works of Chalepas’s latest period. In 1930, he was elected regular member of the Academy of Athens.

His exhibition activity includes solo and group exhibitions, including events at the Parnassos Hall and exhibitions by the Greek Society of Artists, as well as the Venice Biennale (1934); a tribute to his work was held during the 1948 Panhellenic exhibition.

His apprenticeship with Georgios Vroutos accounts for the neoclassicist qualities in his work; moreover – even in his earliest works – the evident preference to mythological and allegorical subjects suggests his affinity with neo-idealist and symbolist trends, with which he had come into contact during his studies in Munich. Thomopoulos, however, is not limited to these, as his oeuvre is informed by an eclectic attitude. Thus, romantic qualities can also be felt, such as his endeavour to capture passion, or his flowing outlines, originating in Rodin, along with realistic qualities, mainly in his busts. His greatest innovation was his coloured sculptures, which he introduced in the 1900’s.