The effects of the ligand used for fabricating palladium (Pd)-incorporated porous polymer composites on their catalytic performances were examined from the perspective of catalysis sustainability. To perform this research, poly(amidoamine) (PAMAM) dendrimers, which were generation zero (G0) and higher, up to G6, the breakdown structure of G0 (that is, the half (G0h) and quarter (G0q)) and a typical small molecule (that is, N,N-dimethyl ethylenediamine (DMEn)) were utilized as ligands. The catalytic performances of the polymer composites were investigated using the aqueous Suzuki–Miyaura carbon cross-coupling reaction as a model reaction. Concerning the efficiency, recyclability and Pd-leaching behavior of the catalytic reaction, polymer composites that were fabricated with PAMAM dendrimers (that is, G1 and higher generations) proved to possess the potential for application as sustainable heterogeneous catalysts. Effects of ligand used for fabricating palladium (Pd)-incorporated porous polymer composites were examined on their catalytic performances (efficiency, recyclability and Pd-leaching behavior). The composites fabricated with poly(amidoamine) (PAMAM) dendrimers (Gn, n≥1) as ligand were proved to have a function that was potentially applicable as sustainable heterogeneous catalysts.