Since joining the European Parliament, Gardiazabal Rubial has been serving as a member of the Committee on Budgets.

[2] In this capacity, she was the parliament's rapporteur on the 2015 budget (along with Monika Hohlmeier) and on the COVID-19 pandemic recovery fund in 2020 (along with Siegfried Mureşan and Dragoș Pîslaru).

[3] In 2019, she drafted (together with Petri Sarvamaa) legislation on cutting EU funds to member states that undermine the rule of law.

[4][5] In addition to her committee assignments, Gardiazabal Rubial is a member of the delegation to the ACP–EU Joint Parliamentary Assembly.

She is also part of the Spinelli Group,[6] the European Parliament Intergroup on LGBT Rights[7] and of the European Parliament Intergroup on Integrity (Transparency, Anti-Corruption and Organized Crime).