Conus tenuilineatus is a species of sea snail, a marine gastropod mollusc in the family Conidae, the cone snails and their allies.
Like all species within the genus Conus, these snails are predatory and venomous. They are capable of "stinging" humans, therefore live ones should be handled carefully or not at all.
The size of the shell varies between 18 mm and 29 mm.
This species occurs in the Atlantic Ocean off Angola.