Novel pyrazole-fused spiro[4H-pyridine-oxindoles] were synthesized under the catalysis of the binary ionic liquid mixture [1,1,3,3-tetramethylguanidinium chloride][1-methylimidazolium-3-sulfonate] in solvent-free conditions. The hitherto unreported binary ionic liquid (BIL) was synthesized via an acid–base reaction and has a melting point much lower than that of the moderate temperature ionic liquid, [1,1,3,3-tetramethylguanidinium chloride], it is made from. The synthesis of the spiro-products was realized via a thermodynamically-favored three-component domino reaction between isatins, 1-phenyl-1H-pyrazol-5(4H)-ones, and 4-aminocoumarin. The domino reaction was highly convergent and functional group tolerant, providing a rapid route to synthesize spiro[4H-pyridine-oxindoles] in fairly high yields from simple bench-stable starting materials. No by-products could be resolved from the reaction mixtures under the optimized conditions.