Apollonio was born in 1935 in Bertoki, a village near Koper. In 1960, he graduated from the Ljubljana Academy of Fine Arts and later specialised in painting. He was a professor of graphic arts at the same academy from 1973 to 1989.
Apollonio's works include landscapes, nudes, and paintings with Istrian themes - the Mediterranean and its culture, history and mythology. Bright colours are one of the most important features of his paintings.
He received several awards at exhibitions in Europe, the US and Japan. In Slovenia, he was honoured with a Preseren Fund Prize for individual achievements in art in 1972 and with a prize at the Ljubljana International Graphic Biennial in 1983. In 1984 he received the Jakopic Award, the highest national award for achievements in the visual arts.
