The community is located between Duluth and Two Harbors on the North Shore Scenic Drive (County 61), at the mouth of the Knife River, from which it gets its name.

Knife River is located 8 miles southwest of the city of Two Harbors.

The boundary line between Lake and Saint Louis counties is nearby.

[3] A separate community of Mellie, located on the east side of the river was platted in 1899 following the building of the Alger–Smith Lumber Company's railroad in 1898; Mellie changed its name to Knife River in 1903.

The SS Benjamin Noble foundered off Knife River in April 1914, with the loss of all hands.