Modification of an enveloped measles virus was achieved by metabolic incorporation of azido sugars in host cells through the protein glycosylation process. Based on this, the resulting measles virus particles could be modified with azido groups on the surface glycoproteins, which could be further labeled with fluorescence dyes using a strain-promoted azide–alkyne cycloaddition reaction. We envision this metabolic labeling approach to be applicable to a wide variety of enveloped viruses, allowing the facile conjugation and surface modification.