Too cute! After Poland, the foursome will be heading to Germany for a visit.
The royal family knows how to make an entrance!
But all eyes will be on the couple's children, George aged three and two-year-old Charlotte, who are getting used to travelling overseas having joined their parents in Canada previous year for an official trip.
Many are viewing the royal trip, taken at the request of the Foreign and Commonwealth Office, as another Brexit diplomacy tour, helping to maintain and strengthen the UK's relations with Europe as it leaves the EU.
The Cambridges will visit Gdansk on Tuesday, after which they will fly to Germany where they will spend one day each in Berlin, Heidelberg and Hamburg.
Kate and William were later seen without the children during an outdoor walk with President Andrzej Duda and his First Lady Agata Kornhauser-Duda where all four were seen laughing as the royal couple took in their surroundings at the gardens of the Presidential Palace.
Even with their solemn expressions, Kate Middleton and Prince William's children completely stole the hearts of everyone who saw them.
In numerous snaps of Prince George disembarking the plane with his family, he can be spotted holding onto his father's hand and gazing at the photographers and dignitaries who awaited the family in Warsaw ahead of their European tour.
William, second in line to the throne, has taken on more public duties in recent years as the queen gradually eases up on her schedule due to advancing years. Warsaw's Belvedere Palace, where they are residing during the visit, has had playground equipment installed. He sported a pair of belted navy shorts (his signature look), a plaid long sleeve shirt, navy socks, and lace-up oxfords.
While in Poland, the couple will tour the former Stutthof concentration camp where 65,000 people were killed. At each location, they will meet survivors of these periods.