Title: Unidentified gamma-ray sources as targets for indirect dark matter detection with Fermi-LAT ABSTRACT: ΛCDM predicts the existence of dark matter (DM) subhalos, some of them not massive enough to retain gas (i.e., baryons) and become visible. If DM is composed of Weakly Interacting Massive Particles (WIMPs), we expect them to annihilate in subhalos, producing gamma rays which can be detected with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope, and appearing as unidentified sources (unIDs) in the gamma-ray sky. We characterize the LAT sensitivity to DM and compare our unIDs sample, filtered according to the expected DM annihilation signal, to predictions from the Via Lactea II (VL-II) N-body cosmological simulation, repopulated with low-mass subhalos below its mass resolution limit. A spectral and spatial dedicated analysis is performed for the best candidates, using 10 years of Fermi-LAT data. Finally, we place conservative and robust constraints on the cross section vs. WIMP mass parameter space.