[en] CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay (0νββ) of ${}^{100}$Mo. In this article, we detail the CUPID-Mo detector concept, assembly and installation in the Modane underground laboratory, providing results from the first datasets. The CUPID-Mo detector consists of an array of 20 ${}^{100}$Mo-enriched 0.2 kg Li${}_2$MoO${}_4$ crystals operated as scintillating bolometers at ∼20 mK. The Li${}_2$MoO${}_4$ crystals are complemented by 20 thin Ge optical bolometers to reject α events by the simultaneous detection of heat and scintillation light. We observe a good detector uniformity and an excellent energy resolution of 5.3 keV (6.5 keV) FWHM at 2615 keV, in calibration (physics) data. Light collection ensures the rejection of α particles at a level much higher than 99.9% – with equally high acceptance for γ/β events – in the region of interest for ${}^{100}$Mo 0νββ. We present limits on the crystals’ radiopurity: ≤3 μBq/kg of ${}^{226}$Ra and ≤2 μBq/kg of ${}^{232}$Th. We discuss the science reach of CUPID-Mo, which can set the most stringent half-life limit on the ${}^{100}$Mo 0νββ decay in half-a-year’s livetime. The achieved results show that CUPID-Mo is a successful demonstrator of the technology developed by the LUMINEU project and subsequently selected for the CUPID experiment, a proposed follow-up of CUORE, the currently running first tonne-scale bolometric 0νββ experiment.