The Mersey River is a river on the north-west coast of Tasmania, Australia. The city of Devonport is situated at the river's mouth on Bass Strait.

It is fed by the Dasher and Fisher Rivers .

Whitewater rafting is popular on the river. The Rowallan Dam hydro-electric station is also located on the Mersey.

It is named for the River Mersey in the United Kingdom.

There is also a Mersey River in the province of Nova Scotia, Canada.