The Duchess of York joined her ex-husband the Duke at a St James's Palace event designed to connect start-up companies with potential investors and mentors.
During the fourth instalment of Adrew's Pitch@Palace programme, 15 budding businesspeople made pitches to a gathering of investors in the hope of drumming up support and making vital connections.
Sarah, Duchess of York spent time socialising with attendees at a reception prior to the event, while the Duke spoke with start-up founders about their respective innovations.
The pair's daughter Princess Beatrice also conversed with participants and guests.
Despite divorcing in 1996, Sarah and Andrew remain close friends.
The programme has been described as a cross between successful television formats Dragons' Den and The X Factor.
In the last 18 months, it has helped generate £103 million of economic activity.
At the beginning of the pitches, the Duke said all 15 participants were part of a larger group that endured "some pretty amazing hell" in a special boot camp at Imperial College in London.
He said: "As far as funding is concerned, I've always said that funding isn't necessarily the only reason for doing this.
"The philosophy of this is much more about being able to put entrepreneurs in touch with decision makers like yourselves."
More than half of the entrepreneurs making pitches hailed from outside London, Andrew told the crowd.
He added: "It shows that the ecosystem in this country as a whole is actually generating some very, very good ideas as a country and it's irrelevant, to some extent, where your geography is."
New technology from one of the companies involved in the programme, Pavegen, is to be installed as a trial in Kensington Palace next year.
The global technology company, which was started six years ago, makes floor tiles that convert the pressure from footsteps into green energy.
Founder Laurence Kemball-Cook took the Duke for a walk over sample tiles at the reception.
He said: "The great thing about the Duke is he really does get technology, engineering and design.
"An entrepreneur speaking to a Duke may be slightly intimidating ... but he completely understood what we're doing and how it worked, and I could talk to him like I talk to a fellow technologist."
Mr Kemball-Cook added: "He made some pragmatic points. It was super interesting talking to him about it - he gets it."