A series of 2H-benzo[g]pyrazolo[3,4-b]quinoline-5,10(4H,11H)-dione derivatives has been synthesized from the three component reactions of 2-hydroxy-1,4-naphthoquinone, aldehydes, and aminopyrazoles in the presence of a catalytic amount of L-proline. This domino reaction proceeds smoothly in good to excellent yields and offers several advantages including no column chromatography, a simple reaction procedure, metal-free reaction conditions and being applicable to a broad range of aldehydes.