Over the past two decades, several glyco-engineering strategies have been successfully explored, including tailoring of the glycosylation pathways for specific applications (e.g. maximizing effector functions of antibodies), and humanization of the N-glycosylation pathway in lower eukaryotes. Unfortunately, all of these approaches still rely on a whole cascade of enzymatic activities to obtain the desired glycan, which ultimately results in heterogeneous and complex glycan mixtures. To resolve this issue, we recently introduced a novel glyco-engineering approach in mammalian protein production cells: GlycoDelete. Minimizing the amount of enzymes involved in Golgi-directed N-glycan maturation resulted in the secretion of homogeneously modified proteins with short sialylated N-glycans. To even further simplify the glycan profile, we generated a second cell line, GlycoDoubleDelete, in which on top of the GlycoDelete N-glycan engineering, mucin-type O-glycosylation is abolished. These glycoprotein production platforms combine the benefits of the native mammalian folding machinery and N-glycan-dependent quality control in the ER with the secretion of homogeneous and minimally glycosylated proteins.