<p>A robust and sustainable catalytic system was developed by immobilizing a Brønsted acidic ionic liquid (BAIL) on sulfonated polyethylene glycol₄₀₀ (PEG₄₀₀-SO₃H) decorated Fe₃O₄ nanoparticles for the efficient synthesis of tetrazolopyrimidine derivatives. The fabrication of the organic–inorganic hybrid catalyst commenced with the formation of an organic zwitterion via the reaction of N-methylimidazole with 1,4-butanesultone leading 1-methyl, 3-butyl sulfonate imidazolium salt. Subsequently, Fe₃O₄ nanoparticle were decorated by PEG₄₀₀-SO₃H to give Fe₃O₄@PEG₄₀₀-SO₃H core–shell nanoparticles. Finally, through a reflux-assisted grafting process in ethanol, organic zwitterion was anchored on Fe₃O₄@PEG₄₀₀-SO₃H support. The resulting hybrid material was meticulously characterized using advanced analytical techniques, including FTIR, ¹H NMR, XRD, SEM, TEM, TGA, BET and EDX confirming its structural integrity. The catalytic efficacy of the prepared hybrid material was demonstrated in a one-pot multicomponent reaction involving aromatic aldehydes, active methylene compounds, and 5-aminotetrazole. Under optimized conditions, the catalyst exhibited exceptional performance, delivering high yields (87–92%) within remarkably short reaction times (15–35&#xa0;min) at a minimal loading of 5&#xa0;mol%. Furthermore, the catalyst’s magnetic properties facilitated facile recovery, while its remarkable reusability was evidenced by sustained activity over four consecutive cycles with negligible loss in yield. Moreover, the introduced anchored BAIL combines the advantages of both heterogeneous and homogeneous catalysis while overcoming the limitations associated with free BAIL.</p> Graphical abstract <p></p>