We propose a dynamical scoto-seesaw mechanism with a gauged $U(1)_{B-L}$. Dark matter is connected with neutrino mass generation, in such a way that the atmospheric scale is generated through the standard seesaw,
while the solar scale is scotogenic, arising through loops from the exchange of dark sector particles. We explain the solar-to-atmospheric scale ratio through this. Dark matter stability follows from the residual matter parity symmetry $M_P = (-1)^{3(B-L)+2s}$, that survives breaking. This model gives rise to significant charged lepton flavour violating (cLFV) processes, including those involving Goldstone boson.