A recyclable and effective polymer-immobilized ligandless palladium catalyst for the Suzuki reaction has been investigated. Palladium nanoparticles are formed in situ and stabilized by poly(N-vinylimidazole-co-N-vinylcaprolactam). A series of aryl bromides have been studied in the reaction with phenylboronic acid under mild conditions with water–alcohol systems as a solvent that complies with “Green Chemistry” demands. The catalyst can be recycled eight times without appreciable loss in activity and a low degree of palladium leaching. Kinetic studies reveal unusual behavior of the reaction; this can be explained on the basis of the observation of changes to the sizes of the particles during recycling, as determined by TEM results. The suggested mechanism of the reaction is in accordance with the concept of the role of leaching in the process.