Neuromorphic electronic devices mimicking the structure and functionality of biological counterparts have shown promising applications in biorealistic computing and bioelectronic interfaces. However, current neuromorphic systems comprising synapses and neurons typically exhibit complex integrated structures and lack chemically mediated characteristics, hindering them from direct biointerfacing. Here, we report a compact artificial synapse-neuron module (ASNM) by seamlessly integrating an organic electrochemical synaptic transistor and a niobium dioxide Mott memristor, showing the chemically mediated synaptic plasticity and highly stable spiking characteristics (>1010 cycles). Sodium ions and dopamine neurotransmitter induce the short-term and long-term plasticity of synaptic transistors, respectively, thus enabling temporary and long-term modulation of the ASNM's firing frequency in a bioplausible range (0–100 Hz). Furthermore, we construct a chemically mediated artificial neuromuscular system based on the ASNM, which could replicate the learning processes of a shooting basketball. These results demonstrate that our ASNM could achieve multiple biorealistic functionalities including sensing, synaptic plasticity, and spiking in a compact structure, providing a promising way for direct biointerfacing.