An efficient and concise practical protocol for the synthesis of novel aza-fused polysubstituted pyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidine derivatives from a readily available aromatic aldehyde, acetophenone and 1H‐Pyrazolo[3,4‐b]pyridin‐3‐amine in presence of Ba(OH)2, under transition metal-free conditions, has been established. This transformation presumably occurs through a sequential Aldol reaction, imine-formation, intramolecular N-cyclization, auto-oxidation sequence of reactions. This protocol, which includes the formation of new C–C and C–N bonds, features a wide substrate scope with a broad range of functional group tolerance.