His stepfather is a Socialist militant,[citation needed] and his grandfather was in the French Resistance during World War II, during which he was shot.

He was among the protesting student leaders during the enormous social movement of 2005 against the CPE law and led negotiations with minister Valérie Pécresse.

[3] From 2013, Julliard served − alongside Myriam El Khomri – as spokesperson for the campaign of Anne Hidalgo, the Socialist Party's candidate for mayor of Paris in the 2014 elections.

[4] During his time in office, he oversaw efforts at the Louvre and Orsay museums in 2016 to move artworks to safety as the rain-swollen river Seine hit its highest level in 30 years.

[6] In 2020, Julliard was recruited by entrepreneur and philanthropist Frédéric Jousset as director of Art Explora, a newly established non-profit foundation.