Cetuximab conjugated fluorescent magnetic nanohybrids (CET-FMNHs) were synthesized for detection of human epithelial cancer via magnetic resonance (MR) and optical imaging. Spherical FMNHs consist of MnFe(2)O(4) magnetic nanocrystals encapsulated in pyrene-labeled PCL-b-PMAA as a surfactant prepared by a nano-emulsion method. FMNHs demonstrated excellent colloidal stability and biocompatibility for biomedical application. Antibody conjugated fluorescent magnetic nanohybrids (CET-FMNHs) served as effective agents for both magnetic resonance (MR) and fluorescence optical imaging of cancer cell lines.