Reported here is a piggyBac transposon-based expression system for the generation of doxycycline-inducible, stably transfected mammalian cell cultures for large-scale protein production. The system works with commonly used adherent and suspension-adapted mammalian cell lines and requires only a single transfection step. Moreover, the high uniform expression levels observed among clones allow for the use of stable bulk cell cultures, thereby eliminating time-consuming cloning steps. Under continuous doxycycline induction, protein expression levels have been shown to be stable for at least 2 mo in the absence of drug selection. The high efficiency of the system also allows for the generation of stable bulk cell cultures in 96-well format, a capability leading to the possibility of generating stable cell cultures for entire families of membrane or secreted proteins. Finally, we demonstrate the utility of the system through the large-scale production (140–750 mg scale) of an endoplasmic reticulum-resident fucosyltransferase and two potential anticancer protein therapeutic agents.