The Willem River or Willem's River was named during the voyage of the Dutch East India Company ship Mauritius in 1618, under the command of Supercargo Willem Janszoon and captained by Lenaert Jacobszoon, and is one of the few features named on a nautical chart made in 1627. It seems reasonable that Willem River was almost certainly named after Supercargo Willem Janszoon, the Commander of the ship Mauritius. Janszoon was captain of the Duyfken in 1605–1606, when part of the Gulf of Carpentaria was mapped, during the earliest documented visit to Australia by a vessel from Europe.