Implementing strategies for single-molecule fluorescence detection in a sheathed flow, NanoFCM provides a versatile and powerful platform —— Flow NanoAnalyzer for the multiparameter analysis of functional nanoparticles (7-500 nm) at the single-particle level. By precise quantification of the ultraweak elastically scattered light from single nanoparticles, high-resolution size distribution comparable to that of electron microscopy can be acquired in 1-2 minutes. Biochemical properties of single nanoparticles can be analysed via concurrent multi-colour fluorescence detection. Flow NanoAnalyzer is therefore expected to become a powerful tool for life science, nanoscience and nanotechnology studies.