Activatable multifunctional nanoparticles present considerable advantages in cancer treatment by integrating both diagnostic and therapeutic functionalities into a single platform. These nanoparticles can be precisely engineered to selectively target cancer cells, thereby reducing the risk of damage to healthy tissues. Once localized at the target site, they can be activated by external stimuli such as light, pH changes, or specific enzymes, enabling precise control over the release of therapeutic agents or the initiation of therapeutic effects. Furthermore, these nanoparticles can be designed to incorporate multiple therapeutic modalities, including chemotherapy, photothermal therapy (PTT), and chemodynamic therapy (CDT). This comprehensive approach facilitates real-time monitoring of treatment efficacy and allows for dynamic adjustments to therapy, resulting in more personalized and effective cancer treatments. This study reports the synthesis of perfluorocarbon (PFC)-encapsulated fluorescent polyepinephrine (PEPP) nanoshells chelated with Fe (PFC@PEPP-Fe) and explores their potential for bimodal imaging and synergistic combination therapy in cancer treatment. The cellular uptake, cytotoxicity, and therapeutic efficacy of PFC@PEPP-Fe were assessed using 4T1 breast cancer cells. bimodal imaging using fluorescence (FL) and ultrasound (US) was conducted after injection into 4T1 tumor-bearing balb/c nude mice. The synergistic anticancer effects of PFC@PEPP-Fe, combining CDT and PTT, were evaluated following 808 nm laser irradiation (1 W/cm²) for 5 min, with treatment outcomes monitored over a 14 days period. Both and studies demonstrated that PFC@PEPP-Fe enables effective bimodal imaging and exhibits substantial anticancer efficacy through the synergistic effects of PTT and CDT. Near-infrared (NIR) laser irradiation increased the temperature, enhancing the release of O and the production of HO, which in turn amplified the CDT effect. The combination of PFC@PEPP-Fe administration and NIR laser significantly reduced tumor volume, slowed tumor growth, and improved survival in 4T1 tumor-bearing mice, confirming the strong anticancer activity due to the PTT/CDT synergy. As a multifunctional theranostic nanoparticle, PFC@PEPP-Fe not only enables cancer cell-specific US/FL bimodal imaging through the generation of microbubbles from its PFC core and fluorescent PEPP shells but also facilitates synergistic chemodynamic and photothermal therapeutic actions under NIR laser irradiation, which induces the self-supply of HO and O within cancer cells.