Izaskun Bilbao was the President of the Basque Parliament in the 2005–2009 term, being elected to the office as a "consensus candidate" among the nationalist majority in the legislature when the incumbent president and initial candidate of her party, Juan María Atutxa, failed to obtain the majority and the election deadlocked.

Bilbao contested the 2009 election as the leading candidate for Biscay in the Basque National Party's ticket, and was subsequently re-elected to parliament.

She served as vice-chairwoman of the Alliance of Liberals and Democrats for Europe Group under the leadership of chairman Guy Verhofstadt until 2019, when Luis Garicano was elected as vice-chairman.

[6] In addition to her committee assignments, Izaskun Bilbao is a member of the European Parliament Intergroup on LGBT Rights[7] and the MEPs Against Cancer group.

[9] She has supported the criticism of Josu Jon Imaz, former EAJ-PNV president and current CEO of Spanish petrochemical company Repsol, against the EU focus on decarbonization and electrification.