The emergence of luminescence nanothermometry in bio and nanomedicine has enabled achievements outside the reach of conventional techniques. For instance, it has provided real-time monitoring to in vivo thermal therapies of tumors, a mandatory requirement for these techniques to work safely and efficiently. However, the reliability of intratumoral thermal readings is currently in question due to the presence of artefacts caused by the inhomogeneous optical properties of biological tissues. This work demonstrates how it is possible to avoid, under specific conditions, these artefacts and reach precise and reliable in vivo intratumoral thermal feedback during in vivo photothermal treatments. The method proposed is based on the use of luminescent nanoparticles capable of multiparametric thermal sensing. The results demonstrate how the convergence of the different thermal readouts becomes a solid indicator of their reliability. It is shown how this new approach makes possible precise (thermal uncertainties below 1 °C) intratumoral thermal feed-back, while simple, efficient, and minimally invasive in vivo thermal treatments of surface tumors is carried out. Results included in this work provide an ingenious route toward the consolidation of luminescence nanothermometry as a convincing technique for high sensitivity preclinical thermal sensing, while also constituting a step toward improved photothermal therapies.