Graphene oxide (GO)-based memristors offer the promise of low cost, eco-friendliness, and mechanical flexibility, making them attractive candidates for outstanding flexible electronic devices. However, their resistive transitions often display abrupt change rather than bidirectional progressive tuning, which largely limits their applications for biological synapse emulation and neuromorphic computing. Here, a memristor with a novel layered structure of GO/pyridinium/GO is presented with tunable bidirectional feature. The inserted organic pyridinium intercalation succeeds in serving as a satisfactory buffer layer to intrinsically control the formation of conductive filaments during device operation, leading to progressive conductance regulation. Thus, the essential synaptic behaviors including analog memory characteristics, excitatory postsynaptic current, paired pulse facilitation, prepulse inhibition, spike-timing-dependent plasticity, and spike-rate-dependent plasticity are replicated. The emulation of brain-like “learning-forgetting-relearning” process is also implemented. Additionally, the instant responses of the memristor can be stimulated by low operational voltages and short pulse widths. This study paves one way for GO-based memristors to actuate appealing features such as bidirectional tuning and fast speed switching that are desirable for the development of bio-inspired neuromorphic systems.