It has been shown previously that the thermoelectric properties of the Zintl phase compound, YbZn2Sb2 can be finely tuned via substitution at the cationic Yb-site. Here we report the results of the investigation of isoelectronic substitution of Zn by Mn in the anionic (Zn2Sb2)2- framework. The p-type YbZn2-xMnxSb2(0.0≤x≤0.4) samples have been synthesized via a solid-state reaction followed by suitable cooling, annealing, grounding, and hot-pressing densification processes. In samples with x=0.0, 0.05, 0.10, 0.15, 0.2, 0.3, and 0.4, the electrical conductivity, Seebeck coefficient, and thermal conductivity measurements have been performed as a function of temperature from 300to750K. It is found that the Mn substitution effectively lowers the thermal conductivity for all samples, while it significantly increases the power factor for x≤0.15. As a result, a dimensionless figure of merit ZT of ∼0.61–0.65 has been attained at 726K for x=0.05–0.15 as compared to the ZT of ∼0.48 in the unsubstituted YbZn2Sb2.