2026 International Symposium on Optical Neural Networks and Neuromorphic Computing (ONNNC 2026) serves as a targeted interdisciplinary forum bridging integrated photonics, brain-inspired hardware, and artificial intelligence architectures, addressing critical power and latency bottlenecks plaguing conventional electronic AI systems. This symposium gathers world-leading academics, device engineers, and industry innovators to exchange frontier breakthroughs spanning silicon photonic neural chips, all-optical synaptic units, optoelectronic neuromorphic arrays, and end-to-end photonic inference frameworks.Distinct from generic computing conferences, ONNNC 2026 prioritizes two core intersecting directions: high-parallelism optical neural network implementation and low-power brain-mimicking neuromorphic hardware empowered by photonics. The agenda includes keynote lectures, themed oral sessions, interactive poster exhibitions, and roundtable dialogues dissecting material limits, chip integration obstacles, and real-world deployment pathways for photonic neuromorphic systems. It fosters long-term global collaborative networks, incubates cross-disciplinary original research, and charts actionable technical roadmaps for next-generation ultra-high-speed, energy-efficient optical AI hardware.