Disclosed are various embodiments for robotic item sortation and optimization along the vertical axis in a conveyor-based system. A robotic system may be mounted above or adjacent to a conveyor system that moves items along a conveyor belt or similar device. Once an item is laterally diverted from the conveyor system, the robotic system may collect the item at a respective holding station and move the item along a vertical axis for placement in one of a plurality of vertically-configured item handling devices.