Clinically, the surgical treatment of bladder cancer often faces the problem of tumor recurrence, and the surgical treatment combined with postoperative chemotherapy to inhibit tumor recurrence also faces high toxicity and side effects. Therefore, the need for innovative bladder cancer treatments is urgent. For the past few years, with the development of nano science and technology, imaging-guided therapy using nanomaterials with both imaging and therapy functions has shown great advantages and can not only identify the locations of the tumors but also exhibit biodistributions of nanomaterials in the tumors, significantly improving the accuracy and efficacy of treatment. In this work, we synthesized Fe(III)-doped polyaminopyrrole nanoparticles (FePPy-NH2 NPs). With low cytotoxicity and a blood circulation half-life of 7.59 h, high levels of FePPy-NH2 NPs accumulated in bladder tumors, with an accumulation rate of up to 5.07%ID/g. The coordination of Fe(III) and the amino group in the structure can be used for magnetic resonance imaging (MRI), whereas absorption in the near-infrared region can be applied to photoacoustic imaging (PAI) and photothermal therapy (PTT). MRI and PAI accurately identified the location of the tumor, and based on the imaging data, laser irradiation was employed accurately. With a high photothermal conversion efficiency of 44.3%, the bladder tumor was completely resected without recurrence. Hematological analysis and histopathological analysis jointly confirmed the high level of safety of the experiment.