This paper describes a flexible microelectrode combined with a neuronal spheroid (neurospheroid) cultured on the electrode tip. Prior works have found that neurons of a neurospheroid can extend their axons to form synaptic connections with neurons inside living neuronal tissues, that could enable such tissues to be stimulated via transplanted neurons (i.e., instead of through the insertion of invasive probes). Here we present a parylene-based flexible microelectrode that enables activation of neurospheroid cultured on the electrode. Experiments revealed that our probe successfully activated neurons within neurospheroids, resulting in neurite extension onto the electrode. These results mark an important step toward achieving minimally-invasive cortical microstimulation via neurospheroid-based probing systems.