The 1st constituency of Ille-et-Vilaine is a French legislative constituency in the Ille-et-Vilaine département.

Like the other 576 French constituencies, it elects one MP using the two-round system, with a run-off if no candidate receives over 50% of the vote in the first round.

Frédéric Mathieu stood for election as a dissident member of LFI, without the endorsement of NFP.