A member of the National Rally (RN), she also held a seat in the Departmental Council of Pas-de-Calais from 2015 to 2021.

In the 2012 legislative election, Beigneux unsuccessfully ran for the National Assembly in the 9th constituency of Pas-de-Calais, placing third with 16.8% of the first-round vote.

Beigneux was fourteenth on the National Rally list for the European Parliament in the 2019 election, thus winning a seat.

In 2015, Beigneux was accused of welfare fraud following the Pas-de-Calais Caisse d'allocations familiales (CAF) opening a litigation case.

She denied having unduly benefitted from the Revenu de solidarité active (RSA) after she left a previous position.