A new smart Pd catalyst was created based on functionalized thermo-responsive poly (N-isopropylacrylamide) (PNIPAM) grafted Fe3O4@CQD@Si. For catalyst fabrication, initially, Fe3O4 magnetic nanoparticle was prepared by co-precipitation method, and then it was coated with CQD as sustainable and environmentally friendly support. Chemical modification of Fe3O4@CQD support with polymerizable groups was performed through vinyltriethylsilan (VTES) reaction. Thereafter, PNIPAM was grafted to the modified Fe3O4 via the conventional free radical polymerization technique. The PNIPAM-grafted Fe3O4@CQD@Si was further treated using hydrazine to create the modified amino support, which was then complexed with Pd(OAc)2 to yield the magnetic heterogeneous catalytic system. All materials are characterized using various methods, i.e., FT-IR, SEM, DLS, CHN, XRD, zeta potential, VSM, and TGA analysis techniques. Fe3O4@CQD@Si@PNIPAM-NH2/Pd catalyst was used to produce a range of substituted alkenes in the Mizoroki-Heck cross-coupling reaction with a high turnover number (TON) and good to outstanding yields. Above the LCST temperature of the PNIPAM, the hydrophobic part of the polymer starts to shrink, and this smart catalyst advances the relevant reactions in milder conditions. Easy purification of the substituted alkenes due to the convenient isolation of the magnetic catalyst with an external magnet is the main characteristic of this process.