Laminaria agardhii is a species of brown kelp, noted by a strong holdfast and finger-like blades.

This species of algae is most commonly found in the northeastern Atlantic Ocean, distribution is as southern as Massachusetts, United States, and northern as Baffin Bay of the Canadian Arctic.

This kelp exists in the sublittoral zone, adapted to grow among tidal rocks of depths between 0.5 and 3 meters.

The blade of the Laminaria agardhii grows to be approximately 30 cm in width, and 3 meters in length.

In addition to promoting thyroid health, members of the family Laminariaceae can be used to induce and aid in labor.