A facile strategy is developed to synthesize dual-modal fluorescent-magnetic nanoparticles (NPs) with surface folic acid by co-encapsulation of a far-red/near-infrared (FR/NIR)-emissive conjugated polymer (PFVBT) and lipid-coated iron oxides (IOs) into a mixture of poly(lactic-co-glycolic-acid)-poly(ethylene glycol)-folate (PLGA-PEG-FOL) and PLGA. The obtained NPs exhibit superparamagnetic properties and high fluorescence, which indicates that the lipid coated on IOs is effective at separating the conjugated polymer from IOs to minimize fluorescence quenching. These NPs are spherical in shape with an average diameter of ≈180 nm in water, as determined by laser light scattering. In vitro studies reveal that these dual-modal NPs can serve as an effective fluorescent probe to achieve targeted imaging of MCF-7 breast cancer cells without obvious cytotoxicity. In vivo fluorescence and magnetic resonance imaging results suggest that the NPs are able to preferentially accumulate in tumor tissues to allow dual-modal detection of tumors in a living body. This demonstrates the potential of conjugated polymer based dual-modal nanoprobes for versatile in vitro and in vivo applications in future.