The 1st constituency of the Seine-Maritime (French: Première circonscription de la Seine-Maritime) is a French legislative constituency in the Seine-Maritime 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.
After 19 years of centre right representation the seat swung back to the Socialist Party in 2012 before then falling to the centrist En Marche! in 2017.