Theuriau obtained a DUT in News-Communication from the Technical University (Institut universitaire de technologie, or 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.