It is native to the Western Pacific Ocean from coasts of China, South Korea, Japan, and southern Russia.

In some non-native habitats, it is an invasive species due to its high growth rate and efficient dispersal.

S. muticum reaches sexual maturity in the summer when gamete production takes place in receptacles.

[6] Originally from Japan, it is thought to have gained worldwide distribution through being transported with Japanese oysters (Crassostrea gigas).

[7] In Europe it extends along the coasts of Great Britain, France, Scandinavia, Baltic Sea, Helgoland, Netherlands, Ireland, the Iberian Peninsula and into the Mediterranean from Italy and the Adriatic.

In many areas, populations of S. muticum grew more aggressively early in its introduction, but shifted to an established species that is integrated with the local ecosystem.

Because of its large size and dense fronds, S.muticum forms a screen within the water column preventing the penetration of light to other seaweeds and algae growing below it.

It fixes itself to the shells of oysters, creating problems in shellfish farming through increased manual work to eliminate the algae.

Like other Sargassum blooms, large mats can detach and wash ashore, where it rots and decreases beach use by people.

Mechanical removal—physically removing S. muticum from surfaces it is growing on—can promote spread of the gametes and seedlings and is labor-intensive if done by hand or cost prohibitive by machine.

Previous studies have shown that Sargassum muticum is able to carry out the biosorption of heavy metals like cadmium,[13][14][15][16] chlorophenolic compounds, and nickel.