We demonstrate precise control of exchange bias (EB) in the ${\mathrm{Nd}}_{2-x}{\mathrm{Sr}}_x{\mathrm{CoMnO}}_{6-\delta }$ $(0\le x\le 1)$ double-perovskite series through ${\mathrm{Sr}}^{2+}$-induced hole doping, revealing a remarkable transition between normal and inverse EB. Using neutron powder diffraction and x-ray absorption spectroscopy, we uncover a structural evolution from a $B$-site-ordered monoclinic $(P{2}_1/n)$ to a disordered rhombohedral $\left(R\overline{3}c\right)$ phase with increasing $x$. This transition is accompanied by a shift in the effective Co valence from $+2$ toward $+3$, while the Mn valence remains close to $+3.6$ throughout the series. DC magnetization measurements indicate a gradual suppression of ferromagnetism with hole doping, whereas ac magnetization measurements for $x=0.75$ reveal pronounced cluster-glass behavior. Notably, $x=0.75$ also exhibits the highest EB field of $\sim 4$ kOe at 8 K under a 20 kOe cooling field. After correcting for minor-loop effects, we identify robust inverse EB at $x=0.75$, persisting even under a 60 kOe cooling field. The coexistence of pronounced glassiness with large EB fields and robust inverse EB suggests that interfacial interactions involving frustrated spins play a central role in stabilizing these exotic EB states. Furthermore, the apparent nonmonotonic evolution of the measured EB with doping is found to be largely influenced by minor-loop effects. After correcting for these effects, the intrinsic EB exhibits an overall reduction with increasing doping and antisite disorder. Interestingly, the intrinsic EB displays a local maximum when the ferromagnetic and nonferromagnetic phase fractions become comparable, despite the persistence of strong glassy dynamics across the series. These findings establish rare-earth double perovskites as a promising platform for engineering tunable EB functionalities through controlled structural disorder and magnetic phase competition, opening new avenues for advanced spintronic and magnetic memory applications.

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• Doping effects
• Exchange bias
• Magnetism
• Perovskites
• Magnetization measurements
• Neutron diffraction
• Susceptibility measurements
• X-ray absorption spectroscopy