The Duke of Sussex was joined by Queen Mathilde at a high-profile dinner in New York on Sunday.
Prince Harry, 40, was pictured during a warm exchange with the Belgian queen, 51, as they attended an event organised by the World Health Organisation (WHO), which focused on "Violence against children and its impact on mental health".
The Duke looked smart in a dark suit with a white open-collared shirt, while Mathilde donned a red shift dress and matching heels.
The pair weren't the only recognisable guests in attendance, which also included British actor Will Poulter and American actor and director, Forest Whitaker.
Harry has began his visit to New York to carry out work with his and wife Meghan's Archewell Foundation, as well as engagements with African Parks, The Halo Trust, The Diana Award and Travalyst.
It comes just days after he appeared at a charity event supporting Santa Barbara's first responders, hosted by actor Kevin Costner.
The Duchess and the couple's two children, Prince Archie, five, and Princess Lilibet, three, have not flown to the Big Apple with Harry.
The Prince of Wales's Earthshot Prize Innovation Summit will also take place on 24 September in New York , but it's understood that William will not be travelling to the US for the event this year.
The Prince and Princess of Wales were pictured on their way to church for the service at Crathie Kirk in Scotland with the King and Queen on Sunday, just two days after William met with essential workers from across the homelessness sector in Aberdeen.
Their appearance comes after Kate was featured in the Court Circular after holding a meeting at Windsor Castle about an issue that aides in the past have described as her life's work – the early years development of children.
She was joined on Tuesday by her household team and staff from the Royal Foundation Centre for Early Childhood, the organisation she established to promote the issue and conduct research.
It is only the third time she has been mentioned in the official record of royal engagements since her health scare began at the start of the year.