The aims of the current study were to synthesize new responsive polymeric microgels with embedded silver nanoparticles and then to employ these particles as catalyst for reduction reactions. To these ends, stimuli-responsive microgels from PNIPAAm and the chitosan derivative were firstly synthesized by free radical precipitation polymerization. Then, silver nanoparticles were synthesized inside these microgel networks by in situ reduction of AgNO3. These microgels were temperature/pH sensitive with a phase transition temperature of 32–35 °C in water at pH = 3 and 8, respectively. The catalytic activity of the Ag nanoparticles for the reduction of 4-nitrophenol can be tuned through the swelling or collapse of the responsive microgel network hosting the active nanoparticles.