Sleaford Bay is a bay located in the Australian state of South Australia on the southern coast of Eyre Peninsula. It was named by the British navigator, Matthew Flinders in 1802.

Sleaford Bay is located on the south coast of Eyre Peninsula in South Australia about 21 kilometres (13 mi) south-west of the municipal seat of Port Lincoln.

It lies between the headland of Cape Wiles at its western extremity and headland of Cape Tournefort at its eastern extremity. A subsidiary bay named Fishery Bay is located on its west side about 2 nautical miles (3.7 km; 2.3 mi) north of Cape Wiles.

The bay was named after the town of Sleaford in Lincolnshire, England by the British navigator, Matthew Flinders in 1802.

The Barngarla name for Sleaford Bay is Dhanana.

The Baudin expedition who visited after Flinders gave it two names – Baudin used the name Anse des Nerlans while Peron and Freycinet revised it to Baie Lavoisier after Baudin's death.

A whaling station located on the coastline within Fishery Bay was in operation from 1839 to 1841.

The coastline of Sleaford Bay is occupied by the locality of Sleaford in the west and by the locality of Lincoln National Park in the east.