  Neutron diffraction, magnetization and muon spin relaxation measurements,
supplemented by density functional theory (DFT) calculations are employed to
unravel temperature-driven magnetization reversal (MR) in inverse spinel
Co$_2$VO$_4$. All measurements show a second-order magnetic phase transition at
$T_{\rm C} = 168$\,K to a collinear ferrimagnetic phase. The DFT results
suggest the moments in the ferrimagnetic phase are delocalized and undergo
gradual localization as the temperature is lowered below $T_{\rm C}$. The
delocalized-localized crossover gives rise to a maximum magnetization at
$T_{\rm NC} = 138$\,K and the continuous decrease in magnetization produces
sign-change at $T_{\rm MR} \sim 65$\,K. Muon spectroscopy results support the
DFT, as a strong $T_1$-relaxation is observed around $T_{\rm NC}$, indicating
highly delocalized spin-carriers gradually tend to localization upon cooling.
The magnetization reversal determined at zero field is found to be highly
sensitive to the applied magnetic field, such that above $B\sim 0.25$\,T
instead of a reversal a broad minimum in the magnetization is apparent at
$T_{\rm MR}$. Analysis of the neutron diffraction measurements shows two
antiparallel magnetic sub-lattice-structure, each belonging to magnetic ions on
two distinct crystal lattice sites. The relative balance of these two
structural components in essence determines the magnetization. Indeed, the
order parameter of the magnetic phase on one site develops moderately more than
that on the other site. Unusual tipping of the magnetic balance, caused by such
site-specific magnetic fluctuation, gives rise to a spontaneous flipping of the
magnetization as the temperature is lowered.
