A law graduate of the University of the Basque Country, Tejeria worked as a solicitor in Tolosa.

As a member of the Women and Youth parliamentary committee, she was one of the promotors of the 2005 Equality Law.

After her party's victory, she was elected as the seventh speaker (President) of the Basque Parliament on 20 November 2012.

Tejeria is also the longest serving member of parliament during the current parliamentary term.

She has also opposed the incarceration of pro-independence Catalan politicians amid the 2017 constitutional crisis.