The emerging field of metrometallomics refers to the qualitative and quantitative measurement of metallic analytes in the metrological sciences. Inductively coupled plasma mass spectrometry (ICP-MS) has the merits of multi-elemental quantification with very low detection limits. It has been applied for the quantification of peptides and proteins by measuring the concentration of certain elements, which is a very important applications area in metrometallomics. This review showcases the application of ICP-MS on the quantification of metalloproteins through the quantification of protein-bound metal/metalloid elements, intrinsic metal/metalloid elements, or labeled metal/metalloid elements. The results of study also suggest that metrometallomics can be a useful tool in the development of certified reference materials of metalloproteins.