Hosting an event at St James's Palace, at which 12 start-up businesses were given the opportunity 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 telephones so that it instead 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'."
The Pitch at Palace project was started by the Duke to help UK start-ups by giving them access to advice and cash from successful business leaders and investors.
"What we're lacking in this area is role models," the prince said previously. "I want to give start-up businesses a boost."