CMC is used in food science as a viscosity modifier or thickener, and to stabilize emulsions in various products including ice cream. As a food additive, it has E number E466. It is also a constituent of many non-food products.

 CMC is also used in pharmaceuticals as a thickening agent. CMC is also used in the oil drilling industry as an ingredient of drilling mud, where it acts as a viscosity modifier and water retention agent.

Insoluble microgranular carboxymethyl cellulose is used as a cation-exchange resin in ion-exchange chromatography for purification of proteins.

CMC is also used in ice packs to form a eutectic mixture resulting in a lower freezing point and therefore more cooling capacity than ice.