We numerically investigate some properties of unbalanced St{u}ckelberg holographic superconductors, by considering backreaction effects of fields on the background geometry. More precisely, we study the impacts of the chemical potential mismatch and St{u}ckelberg mechanism on the condensation and conductivity types (electrical, spin, mixed, thermo-electric, thermo-spin and thermal conductivity). Our results show that the St{u}ckelbergs model parameters $C_{alpha}$ and $alpha$ not only have significant impacts on the phase transition, but also affect the conductivity pseudo-gap and the strength of conductivity fluctuations. Moreover, the effects of these parameters on a system will be gradually reduced as the imbalance grows. We also find that the influence of $alpha$ on the amplitude of conductivity fluctuations depends on the magnitude of the both $C_{alpha}$ and $deltamu/mu$ in the electric and thermal conductivity cases. This results in that increasing $alpha$ can damp the conductivity fluctuations of an unbalanced system in contrast to balanced ones.