Valladares is a member of the Association of Magistrates of the Americas with experience in electoral justice affairs.

She is the only daughter of Justo Valladares Orellana and Lily Moyano Álvarez, both teachers.

Later, she entered the Pontificia Universidad Católica de Chile, where she studied law with professors such as Hernán Larraín and Arturo Aylwin.

Three years later, she joined the Elections Qualifying Tribunal of Chile (Tricel) to participate in the preparations for the 1988 national plebiscite.

In 2021, President Sebastián Piñera assigned her the task of leading the installation ceremony of the Constitutional Convention on 4 July.