Who's a good boy?
The golden trio have put all their royal power behind the day with Heads Together, an initiative aimed at reducing the stigma of mental health issues.
Hosting a reception a reception at Buckingham Palace in London, Wills, Kate and Harry met with the many incredible supporters of and contributors of the charity, which they launched in 2016.
But there was one very cute four-legged pal that was eager to chat to Meghan Markle's leading man - Cooper, the service dog.
The ridiculously charming Labrador-Retriever mix was joined by his owner former marine Phil Eaglesham.
Cooper helps Phil with a range of everyday tasks like opening doors and loading a washing machine.
The cute pooch also happens to be an expert at shaking hands, something the 33-year-old royal got to experience first-hand. Or should that be paw?
Phil told People that Cooper "recognised Harry straight away and got so over-excited."
"Dogs are a very good judge of character — they can smell when something’s wrong."
Before adding about the former Captain Wales, "We all look up to him for doing this. He’s young and been in war zones and has experienced being in the same sort of areas. And that means a lot to veterans who may be struggling. He knows what people are going through."
While we're a little caught up with our favourite pooch and Prince friendship, Tuesday also saw Duchess Catherine step out for the very first time since announcing she's expecting her third child.
It's been nearly two months since we've see Kate and the pregnant mum looked stunning in a baby blue Temperley London dress.
The 35-year-old has been forced to miss a number of important events - including her son’s first day at school -- owing to extreme morning sickness or ‘hyperemesis gravidarum.’
A palace aide told royal reporter Victoria Murphy that, “The Duchess’s condition is improving but she is still suffering from hyperemesis gravidarum.”
Watch Kate step out for the first time since revealing she is expecting!
Prince William delivered a speech at the important event, revealing that it was his wife Kate who was the brainchild behind Heads Together. The organisation, spearheaded by the golden royal trio, aims to break down the stigma around mental health.
"Today, we are here to say thank you. Thank you to everybody,” he began. “When Catherine, Harry and I launched Heads Together, it is fair to say that we were ambitious about what it could achieve.”
"It was Catherine who first realised that all three of us were working on mental health in our individual areas of focus.”
Check out Prince Harry discuss his incredible new initiative to smash the stigma around mental health!
"She had seen that at the core of adult issues like addiction and family breakdown, unresolved childhood mental health issues were often part of the problem.”
"Harry had seen that it wasn’t enough to help veterans recover from their physical injuries without acknowledging the emotional and mental support they required.”
"And after years of working with the homeless, and having been called out to multiple scenes of suicide as a Search and Rescue and then HEMS pilot, I understood the damage poor mental health was causing to our communities and for our families."