The glass plate engraving was discovered in the ancient town of Castulo, in Andalusia.
Specialists have reconstructed the plate from fragmented pieces found inside a religious building abandoned during the fifth century.
The plate, measuring 22cm across, is thought to have been used to hold Eucharistic bread.
In it, the figure (believed to be Jesus) is flanked by two apostles, most likely Peter and Paul.
The man depicted is clean-shaven, with short curly hair and wearing what seems to be a philosopher's toga.
Jesus traditionally always depicted with a beard.