Means for improving the effector functions of current immunotherapeutic antibodies through targeted hyper-glycosylation of the antibody Fc region are disclosed, as well as antibody variants having hyper-glycosylated Fc regions. Fc receptor-mediated effector functions have been shown to be a critical contributor to the efficacies of numerous therapeutic antibodies currently in clinical use. Targeted hyper-glycosylation of antibodies has the potential to significantly improve current immunotherapies for cancer.