In present work, magnetic iron oxide@polypyrrole-nitrogen doped graphene quantum dots (Fe3O4@PPyNGQDs) ternary nanocomposite having high quantum yield and excellent photothermal activity was synthesized. The morphological and chemical structure of the prepared nanocomposites were characterized by Fourier transform infrared (FTIR), Transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), magnetic hysteresis measurement (VSM), and high-resolution transmission electron microscopy (HRTEM). To determine fluorescence properties, the nanocomposite was excitated at different wavelengths and the quantum yield of the ternary nanocomposite was obtained as 6.5 %. The effects of laser power density and concentration of aqueous dispersion of photothermal agents on the photothermal properties in the near-infrared (NIR) region (808 nm) were investigated. Fe3O4@PPy-NGQDs ternary nanocomposite exhibited very high photothermal performance with excellent photothermal stability. The maximum temperature difference (Delta T-max) of aqueous dispersion (0.1 mg/mL) reached up to 19.1, 30.1, and 36.9 degrees C under irradiation of the 808 nm NIR laser at 1.5, 2.0 and 2.5 W/cm(2) power density for 10 min. In summary, due to having excellent photothermal performance and high quantum yield, Fe3O4@PPy-NGQDs nanocomposite is highly promising in simultaneous bioimaging and photothermal treatment practices.