The boom of nanotechnology has yielded exciting developments in designing new kinds of colorimetric immunoassays. These nanomaterial-associated immunoassays have shown great potential for clinical translation and a number of them have already been implemented for testing patient samples from the clinics. Different from most reviews where researchers typically focus on a specific type of nanomaterial or describe assays based on the types of materials, we classify these assays by the function of nanomaterials, focusing on reviewing the distinct phenomenon of nanomaterials and how these properties are utilized to overcome limitations faced by traditional colorimetric immunoassays. We also discuss the challenges and give our perspectives in this field.