In this paper, two nitrite ion sensing nanocomposites based on a magnetic-emissive core–shell structure were designed and synthesized, using Fe 3 O 4 particles as core, a silica molecular sieve (MCM-41) as supporting matrix and two rhodamine derivatives as chemosensors, respectively. These two composite sensing samples were characterized carefully by means of electron microscopy, mesoporous analysis, magnetic response, IR spectra and thermal stability analysis. Emission of these two composite sensing samples was found quenchable by nitrite ion, with limit of detection as low as 1.2 μM. Detailed analysis suggested that these chemosensors followed a static sensing mechanism towards nitrite ion through an additive reaction. These chemosensors could be recycled and recovered by sulphamic acid after nitrite ion sensing.