  The Scotogenic model is an economical scenario that generates neutrino masses
at the 1-loop level and includes a dark matter candidate. This is achieved by
means of an ad-hoc $\mathbb{Z}_2$ symmetry, which forbids the tree-level
generation of neutrino masses and stabilizes the lightest $\mathbb{Z}_2$-odd
state. Neutrino masses are also suppressed by a quartic coupling, usually
denoted by $\lambda_5$. While the smallness of this parameter is natural, it is
not explained in the context of the Scotogenic model. We construct an
ultraviolet completion of the Scotogenic model that provides a natural
explanation for the smallness of the $\lambda_5$ parameter and induces the
$\mathbb{Z}_2$ parity as the low-energy remnant of a global $\rm U(1)$ symmetry
at high energies. The low-energy spectrum contains, besides the usual
Scotogenic states, a massive scalar and a massless Goldstone boson, hence
leading to novel phenomenological predictions in flavor observables, dark
matter physics and colliders.
