A new one pot two-step domino protocol for the efficient synthesis of novel fluorescent benzo[a]phenazine fused derivatives has been developed. The synthesis was achieved by reacting 2-hydroxynaphthalene-1,4-dione, ortho-phenylenediamines, aromatic aldehydes and cyclic 1,3-dicarbonyl compounds in the presence of a catalytic amount of p-TSA in PEG-400 at 70 °C. The structural assignment has been unambiguously confirmed by X-ray analysis. The present finding provides an efficient and promising synthetic strategy for the synthesis of libraries with functional group diversity.