The couple posed for a picture with their new passports alongside Greek Prime Minister Kyriakos Mitsotakis and his wife.
The PM posted the picture on Instagram on Saturday. Hanks and Wilson "are now proud Greek citizens", he wrote.
Greek media said the meeting took place on Paros, an island in the Aegean Sea.
Hanks, Wilson and their children were granted honorary Greek citizenship last year for their role in bringing attention to a devastating wildfire near Athens in July 2018.