Nanoparticle applications in medicine have seen a tremendous growth in the past decade. In addition to their drug targeting application and their ability to improve bioavailability of drugs, nanoparticles can be designed to allow their detection with a variety of imaging methodologies. In the current study, we developed a multimodal nanoparticle platform to enable imaging guided therapy, which was evaluated in a colon cancer mouse model. This "theranostic" platform is based on oil-in-water nanoemulsions and carries iron oxide nanocrystals for MRI, the fluorescent dye Cy7 for NIRF imaging, and the hydrophobic glucocorticoid prednisolone acetate valerate (PAV) for therapeutic purposes. Angiogenesis-targeted nanoemulsions functionalized with αvβ(3)-specific RGD peptides were evaluated, as well. When subcutaneous tumors were palpable, the nanoemulsions were administered at a dose of 30 mg of FeO/kg and 10 mg of PAV/kg. MRI and NIRF imaging showed significant nanoparticle accumulation in the tumors, while tumor growth profiles revealed a potent inhibitory effect in all of the PAV nanoemulsion-treated animals as compared to the ones treated with control nanoemulsions, the free drug, or saline. This study demonstrated that our nanoemulsions, when loaded with PAV, iron oxide nanocrystals, and Cy7, represent a flexible and unique theranostic nanoparticle platform that can be applied for imaging guided therapy of cancer.