Acushnet was first settled in 1659. It has been included as a part of three separate towns throughout its history. It was formerly the northeastern section of the town of Dartmouth, which included the towns of Westport, New Bedford, and Fairhaven. In 1787, New Bedford separated from Dartmouth, and included the lands of Fairhaven and Acushnet. In 1812, Fairhaven was incorporated as a separate town, again including the lands of Acushnet. Finally, the town was officially incorporated in 1860. The name "Acushnet", which is also the name of the river the town lies on, comes from the Wampanoag Cushnea, meaning "peaceful resting place near water", originally designating the fact that the tribe which sold the land to the Puritans inhabited the lands leading up to the river.
In 1841, Herman Melville joined the crew of the whaler Acushnet. He later wrote about his travels at sea culminating in the novel Moby Dick.
In 1910, the Acushnet Process Company (now the Acushnet Company), was founded in the town, and continues to be one of Southeastern Massachusetts's most enduring industries. The Acushnet Company owns the Titleist brand name, under which golf balls, golf clubs, and other golf paraphernalia are marketed.