Groundbait is a fishing bait that is either thrown or "balled" into the water in order to olfactorily attract more fish to a designated area (i.e. fishing ground) for more efficient catching via angling, netting, trapping, or even spearing and shooting. Groundbaits are typically scattered separately from the hook and usually before even casting any rod or net, although in bottom fishing they can be deployed synchronously with hookbaits while contained inside a gradual-release device also attached to the fishing line known as a method feeder.

Groundbaits are often used in freshwater coarse fishing (where the target fish are commonly omnivorous or algivorous and might not be easily drawn to the hookbait), and can be custom-made personally by the angler or bulk-purchased from dedicated manufacturers. There are many different recipes of groundbaits that can be used to target specific species of fish. Groundbait can differ by the sizes of the crumbs, type of seed, colour and smell. The angler can also mix additives to the groundbait to alter its firmness in order to control the rate of bait release or breakdown once in the water.

Groundbaits used in blue water fishing are known as "chums", which consist of freshly cut parts of a slaughtered fish often added with blood and offals, in order to attract large predatory fishes.