Molyneux Bay is a bay on the south east coast of the South Island in the Otago Region of New Zealand.

It stretches for some 12 kilometres (7.5 mi) and is bounded in the northeast by a small promontory close to Summer Hill and in the southwest by the headland of Kaka Point.

The name of the bay first appears on James Cook's charts mapped during his first voyage.

It was named after Robert Molyneux (or Molineux), the sailing master of HMS Endeavour, who died on the return voyage to England.

[2] The former settlement of Port Molyneux stood on the shore of Molyneux Bay until a major flood altered the course of the river, making the port unviable.