Sepia novaehollandiae is a species of cuttlefish native to the southern Indo-Pacific. Its natural range stretches from Shellharbour, New South Wales (34°35′S 150°52′E / 34.583°S 150.867°E / -34.583; 150.867) to North West Shelf in Western Australia (18°57′S 118°45′E / 18.950°S 118.750°E / -18.950; 118.750). It lives at depths of between 15 and 348 m.
The type specimen was collected off Kangaroo Island, South Australia (35°50′S 138°03′E / 35.833°S 138.050°E / -35.833; 138.050). It is deposited at the Muséum National d'Histoire Naturelle in Paris. The species was described by Hoyle in 1909.
Sepia novaehollandiae is known to grow to a mantle length of 77 mm, but specimens from Spencer Gulf reach mantle lengths of around 125 mm and larger specimens of cuttlebones reaching lengths of 170 mm have also been found.
Fishery dependent and independent data from Spencer Gulf has shown that largest populations of sexually immature Sepia novaehollandiae are caught between February and May annually. No data was published for months July–October or January.
