Protein glycosylation greatly influences the structure, function, and pharmacokinetics of recombinant proteins. Here, growth media supplemented with metal ions is shown to modulate the protein glycosylation profile of recombinant proteins expressed in a variety of eukaryotic cell lines. In particular, millimolar amounts of ferric salts (e.g. ferric nitrate, ferric citrate, etc.) significantly increased the percentage of galactosylated N-glycan species. The effect on protein glycosylation was concentration-dependent manner up to 1.0 mM across multiple cell lines without adverse effects on cell viability. The use of iron supplements in cell culture media provides an efficient and effective approach towards the specific re-targeting of N-glycan glycoform profiles of recombinantly expressed proteins.