"It's important for us to be here. We have a long and shared history," Harris told Macron before the ceremony at the foot of the Arc de Triomphe.
Harris' attendance at the ceremony comes after a meeting with Macron on Wednesday (November) at the Elysee presidential palace as part of a four-day visit aimed at restoring ties strained by a submarine deal that left France in the lurch.
Holding hands with Macron on Thursday, Harris said she "liked" the discussions with the president, adding that they have "covered a lot of ground."
During Thursday's ceremony, Macron paid tribute to Hubert Germain, the last surviving member of an order honouring heroes of France's liberation during World War Two who died in October.