Laser ablation (LA) has shown promising results in selective treatment of solid tumors. Recently, nanomaterials, in particular nanoparticles (NPs), have been proposed as mediators for laser tissue ablation due to their high optical absorption coefficients. In this work, we report distributed fiber optic temperature sensors for monitoring of NPmediated LA in ex-vivo porcine liver. This study aims at improving the outcomes of LA through magnetite NPsenhanced LA with in-situ thermal profiling. Such thermal profiling is achieved with optical backscatter reflectometer interrogating a set of custom-made MgO-doped optical fibers exhibiting enhanced scattering profiles. Fiber optic sensors, providing spatially resolved measurements, significantly outperform conventional thermocouples and imaging techniques. A minimally invasive LA setup is based on high power fiber coupled diode laser operating at 980 nm wavelength, with output power up to 30 W. Magnetite (Fe3O4) NPs are synthetized and locally injected within the tissue before performing LA. The sensing setup utilizes optical backscatter reflectometer that exploits Rayleigh backscattering to measure the temperature distribution with submillimeter spacing. Thermal maps, i.e. temperature distribution as a function of space and time, are reported highlighting thermal distribution within the ablated lesion and in off-target adjacent tissue. The influence of laser power and of NPs concentrations on the outcomes of LA is also investigated. Results demonstrate that injection of NPs into targeted area helps enhance conversion of light energy into thermal energy, thus increasing the efficacy of the ablation within the treated area, without overheating the adjacent off-target tissue.