Kate stepped out in a Chanel coat for a visit with William to a historic military hospital on the final day of their visit to the French capital.
They met French Second World War veterans at Les Invalides as well as victims and members of the emergency services from the Bataclan and Nice attacks.
As the couple toured the hospital, reports came in of a terrorist attack at Paris Orly Airport but there was no apparent change to the royal’s schedule.
On Friday, during a busy first day in Paris, Kate wore a dazzling gown to a dinner staged in the royal couple’s honour while William reassured his hosts that British-French relations are secure despite Brexit.
William’s recent “lads-only’’ weekend trip, which was criticised by the press, has overshadowed the two-day visit, and at one point a song featured during the Verbier break was sung by a choir performing at the dinner.
But the Duke remained relaxed and smiling throughout Friday and did not react when the Pharrell Williams hit Happy was performed.
Speaking during the launch of Les Voisins - a celebration of UK-French links - the second in line to the throne told young French leaders from a range of fields: ‘’Our two nations continually inspire one another to become better: more creative, more prosperous, more innovative.
“This partnership will continue despite Britain’s recent decision to leave the European Union. The depth of our friendship and the breadth of our co-operation will not change.’’
The two-day visit comes in the month Prime Minister Theresa May is expected to trigger Article 50, beginning Brexit negotiations.
William and Kate’s trip will be seen as a bid to build on the UK’s relationship with France and they have already been dubbed ‘’Brexit ambassadors’’ by the press.
Kate disappointed fashion watchers by arriving in the French capital in the same Catherine Walker coat she wore earlier on Friday to an Irish Guards event in London celebrating St Patrick’s Day.
But for an embassy reception, she wore a chic sleeveless black outfit by Alexander McQueen and changed into her third outfit, the glittering Jenny Packham gown, for the dinner at the British ambassador’s residence.
Among the guests were movie stars Kristin Scott Thomas, Audrey Tautou and Jean Reno.
Before leaving Paris, William and Kate will be guests at the Six Nations rugby match between France and Wales at the Stade de France.