The Danish Royal Court has released a photo of Prince Christian to mark this milestone as a teenager on 15 October 2018.
Prince Christian, who is second in the line of succession for the Danish throne, was born in 2005 at 1:57 am in Rigshospitalet, the Copenhagen University Hospital, in Copenhagen.
He is the eldest son of Crown Prince Frederik and Crown Princess Mary and the first member of the Royal Family to attend a state school.
Scandinavian Airline Systems named an A319 aircraft, the Christian Valdemar Viking, in his honour in 2006.
Prince Christian helped fly the Invictus Games Sydney 2018 with his parents, younger sisters and brother on 11 October.
Crown Prince Frederik will support the Danish veterans participating from 20 to 27 October 2018.