Abstract: This invention provides the nucleic acid molecules encoding novel small monomeric near-infrared fluorescent protein miRFP670nano, variants and derivatives thereof as well as proteins and peptides encoded by these nucleic acids. The invention also relates to derivatives, homologues, or mutants of the specific proteins referenced above as well as fragments of the nucleic acids and the peptides encoded thereby. The invention further relates to host-cells, stable cell lines and transgenic organisms comprising above-referenced nucleic acid molecules. The present invention also refers to methods of making and using small monomeric near-infrared fluorescent proteins derived from cyanobacteriochromes. The presented protein and its derivatives find use in a variety of applications and approaches, including labeling of biomolecules, cells or cell organelles, detecting protein-protein interactions, and generation of genetically encoded fluorescent biosensors.