Carbohydrates are essential mediators of many important extracellular binding events. Multivalent effects are often required for these binding interactions that are generally weak. Biologically significant carbohydrate-modified nanomaterials are an appealing model system for a systematic investigation of multivalent binding effects. This review seeks to highlight recent striking examples of multivalent glycosylated nanomaterials concentrating on carbohydrate-protein interactions. The specific aim is to provide an overview of various aspects of glyco-nanoparticles in binding assays, targeted therapy, molecular imaging, enzyme activity assay, and bacterium detection.