Theuriau obtained a DUT in News-Communication from the Technical University (IUT) Pierre Mendès-France in Grenoble, and later a Master's degree in Audiovisual Journalism from the Institute of Communication and Media (ICM) at Échirolles.

Theuriau was a reporter at Match TV in 2002. Since 2003, she has been a reporter and anchor for La Chaîne Info, where she became better known to the French general public. She made her breakthrough as a newscaster and travel show host for LCI, the news channel and for TF1. Her programs were LCI Matin (LCI Morning), the 6:40 news on LCI and TF1 from Monday to Thursday and the Voyages travel show on Wednesdays at 13:55 on LCI.

In May 2006, she surprised the management of TF1 by refusing the offer to be the anchorwoman of the weekend evening news of TF1, as a summer replacement for sitting anchorwoman Claire Chazal. In June 2006, M6, another French television channel, announced her arrival for September as editor-in-chief and presenter of Zone interdite, a weekly magazine show featuring investigative reporting. She also presents Un jour, une Photo and Deux, trois jours avec moi on the French TV channel Paris Première, in partnership with Paris Match. Un jour, une photo features stories behind iconic and historic photos. Deux, trois jours avec moi is a weekly travel programme in which an invited guest reveals more about him or herself during a trip.

Since September 2006, she has been a writer in chief and anchor of the TV magazine Zone interdite ("Forbidden Zone") on Métropole 6.

In March 2007, she launched, with five other journalists (Claire Chazal, Marie Drucker, Laurence Ferrari, Béatrice Schönberg, and Tina Kieffer), the organization “La Rose”, which works with UNICEF to help educate girls.