In present study we have designed and synthesized novel cellulose supported ionic liquid catalyst (CSILC), [Cell@Al2O3(HEPiPY)]DCA and explored its catalytic efficiency for synthesis of novel 11b,12‐dihydro‐6H,13Hbenzo[5,6][1,3]oxazino[3,4‐a]quinazoline‐6,13‐diones by performing the one pot reaction of 2‐(2‐hydroxyaryl)‐2,3‐ dihydroquinazolin‐4(1H)‐one and 1,1‐carbonyl diimidazole (CDI). The catalyst was characterized by diverse analytical techniques viz. Fourier‐Transform Infrared Spectroscopy (FT‐IR), Scanning Electron Microscopy (SEM), Energy Dispersive X‐ray Analysis (EDX) and Thermo Gravimetric Analysis (TGA). The biological activities of synthesized novel derivatives were evaluated along with in silico assessments against the vascular endothelial growth factor receptor‐2 (VEGFR‐2) target, in which the results were considerable. The catalyst exhibited remarkable reusability up to six consecutive runs without considerable loss in the catalytic activity.