Structural, magnetic and transport behavior of Nb substituted Fe₂Val alloys have been investigated in the present work. From the detailed analysis of these data it is observed that Nb content promotes a lattice expansion in L2₁ super-structure of Fe₂VAl. Magnetization data suggest that un-doped Fe₂VAl exhibits cluster glass behavior with a bimodal distribution of super paramagnetic clusters at lower temperatures, developed possibly due to the cluster size distribution. However, in Nb-substituted alloys, cluster size reduces and cluster density increases, which further reduces coupling between the clusters, resulting in a state of increased magnetic disorder upto aplausible 20% substitution. Concurrently resistivity increase sat lower temperatures and shows a deviation from semiconductor like transport, which can be explained in terms of increasing spin dependent scattering and decreasing inter cluster interactionduetoiso-electronic-but-larger-sizedNbsubstitutionatVsite. Present experimental results corroborate well with the theoretical predictions made in the literature.