The 3rd constituency of Somme is a French legislative constituency in the Somme 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.

The 3rd constituency of the Somme stretches along the entire length of the department's coast as well as reaching into its centre close to Amiens.

The seat is extremely marginal and has swung between left and right throughout the Fifth Republic.