This study examines the microstructural evolution of a non-equiatomic NbCrTiMoVHf refractory complex concentrated alloy (RCCA) during isothermal exposure at 1200 °C for 1–96 h. The as-cast microstructure showing dendritic with interdendritic (ID) segregation. Dendrite cores are enriched in Nb, Mo, and V, forming a refractory BCC matrix, whereas ID regions are enriched in Hf and Cr; Ti preferentially decorates dendrite peripheries and ID interfaces. A 1 h anneal produces nanoscale precipitates concentrated along ID boundaries. By 24 h, Cr/Hf-rich C15 Laves phase is well established in ID regions, while the dendritic BCC matrix remains Nb/Mo/V-rich. With further aging to 72 h, precipitates coarsen via diffusion-controlled Ostwald ripening and chemical partitioning intensifies. After 96 h, Laves-type precipitates nucleate within dendrite interiors, indicating a breakdown of the original matrix–ID partitioning and the onset of microstructural instability. XRD analysis corroborates these trends as HfV2 (C15) is detectable in the as-cast condition and persists under all heat-treatment durations, with peak intensities increasing at longer exposures. Concurrently, reflections from a Ti-based solid solution (TiSS) and Mo/Nb-rich BCC phases evolve with time, while non-equilibrium Cr-related peaks present in the as-cast state disappear after extended annealing. Overall, casting-induced heterogeneity governs early precipitation, and prolonged exposure drives progressive redistribution of Hf/Cr into HfV2-type intermetallics. These results underscore a trade-off between strength contributions from refractory-rich phases and reduced long-term high-temperature stability due to continued Laves formation and intradendritic precipitation.