Hosting an event at St James's Palace, at which 12 start-up businesses were given the chance to woo investors, the Duke seized the opportunity to snap a shot of himself and the assembled delegates.
He told the 350-strong audience: "This is a unique day at the palace because we are encouraging you to use your phones and electronic gadgetry. As a result of that I've decided there's a bit of a thing going around about selfies."
The Duke then produced his smartphone and snapped the shot that has since been shared more than 181 times.
The Duke had earlier defaced a sign banning mobile phones so that it read 'Mobile phones are allowed inside the State Rooms'.
A Buckingham palace source said: "This was a tech-heavy event and the Duke quickly got into the spirit of things.
"He resisted the temptation to refer to the royal photograph as a 'onesie'."