The corticospinal tract is a complex system of paramount importance for the control of voluntary movements. It originates in the cerebral cortex from upper motor neurons which directly contact the lower motor neurons located in the ventral horns of the spinal cord. Lower motor neurons, in turn, form synapses with skeletal muscle cells delivering the signal generated in the brain. Insults to this system, such as spinal cord injuries or amyotrophic lateral sclerosis, cause dysfunction and degeneration of motor neurons leading to severe and untreatable pathological conditions. We aim to explore these damages with a human 3D model that recapitulates the corticospinal tract in vitro. To achieve this goal, we derived brain and spinal cord organoids from human iPSCs. Brain organoids showed the formation of ventricle-like structures and a temporal expression marker switch from neural stem cells to cortical neurons. We implemented the protocol with the addition of the leukemia inhibitory factor (LIF) enhancing the presence of outer radial glial cells and the thickness of the outer sub-ventricular zone. Spinal cord organoids were generated following an innovative accelerated protocol oriented toward a cervical motoneuronal patterning. After only 28 days of differentiation, they expressed high levels of progenitor and mature motor neuron markers. By connecting the two types of organoids we obtained corticospinal assembloids in which projections spanning from the brain to the spinal portion were observable. This system represents a valuable platform to explore traumatic and neurodegenerative diseases affecting the corticospinal tract and develop new therapeutic approaches.