Osprey Reef is a submerged atoll in the Coral Sea, northeast of Queensland, Australia. It is part of the Northwestern Group of the Coral Sea Islands. Osprey Reef is roughly oval in shape, measuring 25 by 12 kilometres, and covers around 195 square kilometres. It has a perimeter of 69.5 kilometres. The central lagoon is only 30 metres deep.
The reef sits atop a seamount in deep water. It is an isolated location some 60 kilometres from other reefs. The almost vertical reef walls, which rise from a depth of about 2,000 metres, are home to a dwarf form of Nautilus pompilius that is isolated from other nautilus populations by more than 100 kilometres. Schindleria brevipinguis, one of the world's smallest fish, is found in the Osprey Reef lagoon.
The reef has no intertidal or emerged sand cay. The surrounding waters are part of the South Equatorial Current. The reef is protected within the Coral Sea Commonwealth Marine Reserve.