From 1989 onwards, Bresso was a member of the provincial, regional and national party executives of the Democrats of the Left.

She stood down at the end of April 2010, after being defeated on her home turf of Piedmont in her country's regional elections.

[1] Shortly after, Claudio Burlando, the president of Liguria and a fellow member of Italy's centre-left Democratic Party, gave up his seat on the Committee of Regions so that Bresso could have it.

In November 2014, Bresso and Elmar Brok were appointed by the committee to explore the possibilities of the eurozone governance reform without any treaty change.

She chaired the European Parliament Intergroup on Rural, Mountainous and Remote Areas (RUMRA).