Ferrofluid can behave like a liquid O-ring as a rotating shaft enters the low or high pressure chamber. The ferrofluid is held in place by permanent magnets and creates a tight seal, eliminating most of a friction produced in a traditional mechanical seal.

Ferrofluid has also found its application in smart fluids, where hydrodynamics is not caused by a pressure difference, but by a magnetic field. This allows for greater control of the fluid flow, e.g. in microreactors.

Ferrofluids improve the acoustic parameters of loudspeakers by concentrating the amount of iron oxide nanoparticles at a given point in the magnetic field. The result is a more muffled sound with a softer overtone.

Ferrofluid is used in magnetic resonance imaging (MRI) as a contrast agent. There is also great hope for future biomedical applications of ferrofluids as drug carriers to a specific location in the body.