Abstract This study determined whether chitin-oligosaccharides and chitosan-oligosaccharides (COS) are suitable acceptor carbohydrates for the LacLM-type β-galactosidase of Lactobacillus plantarum. Enzymatic reactions were carried out with lactose as galactosyl-donor and chitinbiose (N,N′-diacetyl chitobiose), chitintriose (N,N′N″-triacetyl chitotriose) or a highly deacetylated COS preparation with a degree of polymerization ranging from 2 to 4 as galactosyl acceptors. Transgalactosylated oligosaccharides were identified by liquid chromatography-mass spectrometry (LC-MS/MS). LC-MS/MS analysis demonstrated formation of mono- and digalactosylated chitinbiose, mono-galactosylated chitintriose, and mono-, di-, and trigalactosylated COS. β-(1→4)-Linkages were formed during the galactosylation of chitinbiose and chitintriose. In conclusion, the conversion of lactose with β-Gal from Lb. plantarum and chitin-oligosaccharides or COS as glycosyl acceptors allows the production of novel oligosaccharides.