The unnamed boy, a member of the Coptic Orthodox Church Centre in Stevenage, Hertfordshire, took the snap as the Prince of Wales chatted to the congregation.
He asked Prince Charles if he could take a photo, then quickly pressed the button before his bodyguards could intervene.
He said: "I went up to him and said if I could take a photograph of him - and then well I didn't wait for the body guards to push me out of the way, I just took a picture."
Prince Charles, who was wearing a navy blue suit and checked tie, is seen standing behind the little boy, looking into the camera.
The Prince was visiting the church to show his support for Christians in the Middle East where for decades there have been a number of conflicts.