A flatbed truck (or flatbed lorry in British English) is a type of truck the bodywork of which is just an entirely flat, level 'bed' with no sides or roof. This allows for quick and easy loading of goods, and consequently they are used to transport heavy loads that are not delicate or vulnerable to rain, and also for abnormal loads that require more space than is available on a closed body. Flatbed trucks can be either articulated or rigid.

A flatbed has a solid bed, usually of wooden planks. There is no roof and no fixed sides. To retain the load there are often low sides which may be hinged down for loading, as a 'drop-side' truck. A 'stake truck' has no sides but has steel upright stanchions, which may be removable, again used to retain the load.

Loads are retained by being manually tied down with ropes. The bed of a flatbed truck has tie-down hooks around its edge and techniques such as a trucker's hitch are used to tighten them. Weather protection is optionally provided by manually 'sheeting' the load with a tarpaulin, held down by ropes. These manual loading techniques are slow and require some care and skill. There is also the risk that an improperly secured load may be shed in transit, often leading to accidents or road blockages. There is also little theft protection for such a load. The slowness of loading loads like this led to the development of more efficient truck designs with enclosed bodies.

Some improvement was made with the general replacement of ropes by flat webbing straps, tightened with a ratchet. These reduced the skill of 'roping up' and improved the control of tension, leading to fewer shed loads.

Flatbeds became rare in the 1980s as the majority of road freight changed to either containers or pallet loads carried on larger and more efficient trucks, optimised for quicker loading by fork-lift trucks. Containers are carried on specialised semi-trailers with twistlocks in the corners to retain the container. Pallet loads are carried in either box bodies, loaded through rear doors, or curtain-sided bodies loaded through the sides. Both of these protect loads from the weather and can be quickly loaded with standard loads, but are more restrictive for single bulky loads, loaded by crane. The haulage and logistics business also changed around the same time as a greater proportion became more regular in nature, such as standard daily loads of equally-sized boxes from a distribution centre to a supermarket, rather than the unpredictable ad hoc nature of earlier road transport.

Flatbeds are still in use, but are now used for more specialised cargoes, such as constructional steelwork or lighter abnormal loads, such as machinery, lumber loads/dry wall or any load that requires use of a forklift without the use of a loading dock.

Low loaders, for construction machinery and heavy plant vehicles, are not considered as flat bed . Neither are abnormal load carriers for heavy haulage.

In North America, the length is commonly 48 or 53 feet (14.63 or 16.15 m), and the width is either 96 or 192 inches (2.44 or 4.88 m) (including rub rails and stake pockets on the sides, which generally placed every 2 feet or 61 cm). Some older trailers still in service are only 45 feet (13.72 m) or shorter if used in sets of doubles or triples (often used to haul hay). Various lengths and combination setups can only be legally driven on turnpike/toll roads which are far too long for most roadways. Body and frame can be one of three general designs: the heaviest and sturdiest is all steel (usually with wood planks), ever-popular combo with steel frame and aluminium bed, these type often have wood portions for nailing down dunnage boards), and aluminium (which is the lightest allowing for more cargo to be legally carried without overweight permits). Incredibly light and very expensive to purchase, all aluminium trailers are very slippery when wet, flex more and are easily damaged. They also have a natural upwards bend so that when loaded they straighten out to be flatter, rather than to sag in the middle under a load.