The artistic style of Ioannis Terzis is that of the fifteenth-century Cretan school of Byzantine art. His paintings are characterized by strong yet beautiful figures and by bold color. His use of color changed from using darker colors to later using lighter and brighter colors.
Terzis worked in various media, including watercolor, oil, and fresco. Some of his most famous works were done on the island of Rhodes, where he completed murals in nine churches. One of these is the 12th century Cathedral of Rhodes. The murals were painted entirely in fresco which was the only such work completed at that time.