The Duke and Duchess of Cambridge praised the courage of two French army members, who described their injuries and the effects the attacks had on their lives.
"You're very brave," Kate told them.
The royal couple also met World War II veterans during a visit to Les Invalides military hospital in Paris.
They toured the Impressionists Gallery at the Musee d'Orsay before watching a rugby match between France and Wales.
The two-day visit does not include official memorial events for Princess Diana, who was killed in a car crash in the city in 1997.
On Friday, French President Francois Hollande greeted the Duke and Duchess at the Elysee Palace, where they discussed the Syrian conflict and the fight against terrorism as well as Franco-British relations, according to a presidential source.
Countries' partnership will continue despite Brexit: William
Speaking at a reception, Prince William said the partnership between the two countries would "continue despite Britain's recent decision to leave the European Union".
"The depth of our friendship and the breadth of our cooperation will not change," he said.
After last June's vote to leave the EU, Britain is about to embark on two years of difficult exit negotiations on whose outcome EU founder member France will have a strong influence.
Prince William, second-in-line to the British throne, has been criticised by some British newspapers this week for going skiing and dancing with friends in the Swiss Alps, missing a service at London's Westminster Abbey attended by other members of the royal family.
The reports revived media criticism the Prince spends too much time enjoying the high life while shirking official tasks.
In an interview last year, he said he was aware of the criticism and was willing to take on more royal duties.