Phytochrome B (phyB) is a plant red light photoreceptor that regulates various developmental processes including germination, seedling photomorphogenesis and shade avoidance response. Upon the absorption of red light, phyB enters the nucleus and forms a membraneless organelle called photobody, suggested to be a site for transcription, protein sequestration and protein degradation. However, which proteins constitute the photobody is still elusive. We report the isolation and the identification of phyB photobody components. We isolated the photobody by adopting the fluorescence-activated particle sorting and analyzed the isolated photobody components with the liquid chromatography-tandem mass spectrometry. Our analysis shows that a phyB photobody is made of about 1,500 phyB dimers and other proteins that could be classified into two groups based on their requirement of other proteins to localize to the photobody in protoplasts. The first group includes proteins that directly interact with phyB and readily localize to the phyB photobody when transiently expressed in protoplasts, while the second group includes proteins that require the co-expression of the first group to localize to the photobody. Together, our results support that phyB photobodies include not only phyB and its primary interacting proteins but also its secondary interacting proteins.