Part of Podemos since the beginnings of the party in 2014 at the Teatro del Barrio, Serra ran 16th in the Podemos list for the 2015 Madrilenian regional election, and became a member of the 10th term of the regional legislature. Her sister Clara was elected in the same election also in the Podemos list. A representative in Madrid of the "anticapitalista" minority faction within Podemos, she ran in the December 2017 primaries for the party leadership in the city of Madrid, where she was defeated by the mainstream candidature led by Julio Rodríguez.