Semicarbazide is used in preparing pharmaceuticals including nitrofuran antibacterials (furazolidone, nitrofurazone, nitrofurantoin) and related compounds.  It is also a product of degradations of the blowing agent azodicarbonamide (ADC).  Semicarbazide forms in heat-treated flour containing ADC as well as breads made from ADC-treated flour.
Semicarbazide is used as a detection reagent in thin layer chromatography (TLC). Semicarbazide stains α-keto acids on the TLC plate, which can then be viewed under ultraviolet light.