Protein glycosylation is a prevalent post-translational modification that plays critical roles in various biological processes. N-glycan, which is linked to the β-amide nitrogen of an asparagine residue, is the predominant form of glycans in eukaryotes. Numerous chemical methodologies have been developed to access such structures, which often require specific expertise and tedious protection/deprotection steps. On the other hand, enzymes (e.g., glycosyltransferase and glycosidase) catalyze regio- and stereo-specific glycosylation reactions, provide powerful tools to access complex glycans. This chapter summarizes enzymes that were employed in the preparation of N-glycans, and recent advances in enzymatic and chemoenzymatic synthesis of N-glycans.