Cy3 is one of the most popular fluorescent labeling dyes for preparing orange-red fluorescent bioconjugates. However, most of the commercial Cy3 labeling kits require intensive hands-on time. This Cy3 ReadiLink™ labeling kit is one of the most robust protein labeling kits for preparing Cy3-labeled antibody conjugates or other protein conjugates. It essentially only requires 2 simple mixing steps without a column purification required. The kit provides all the essential components for labeling ~2x50 ug antibody. Each of the two vials of Cy3 dye provided in the kit is optimized for labeling ~50 µg antibody. This Cy3 protein labeling kit provides a convenient method to label monoclonal, polyclonal antibodies or other proteins (>10 kDa).