This study investigates the brain-wide dynamics linking sensation to action during decision-making in mice. Using dense silicon electrode recordings, researchers observed that sensory evidence is integrated across multiple brain regions, including the visual system, frontal cortex, basal ganglia, thalamus, cerebellum, and midbrain. The integration of sensory evidence occurs in sparse neural populations that drive movement-preparatory activity. Visual responses evolve from transient activations in sensory areas to sustained representations in frontal-motor cortex, thalamus, basal ganglia, midbrain, and cerebellum, enabling parallel evidence accumulation. In areas that accumulate evidence, shared population activity patterns encode visual evidence and movement preparation, distinct from movement-execution dynamics. Activity in movement-preparatory subspace is driven by neurons integrating evidence, which collapses at movement onset, allowing the integration process to reset. Across premotor regions, evidence-integration timescales were independent of intrinsic regional dynamics, and thus depended on task experience. Learning aligns evidence accumulation to action preparation in activity dynamics across dozens of brain regions, leading to highly distributed and parallelized sensorimotor transformations during decision-making. This work unifies concepts from decision-making and motor control fields into a brain-wide framework for understanding how sensory evidence controls actions. The study shows that sensory evidence is transformed into goal-directed actions through widespread, distributed, and parallelized neural processes. The findings highlight the role of learning in shaping these processes and the importance of brain-wide dynamics in linking sensation to action during decision-making.This study investigates the brain-wide dynamics linking sensation to action during decision-making in mice. Using dense silicon electrode recordings, researchers observed that sensory evidence is integrated across multiple brain regions, including the visual system, frontal cortex, basal ganglia, thalamus, cerebellum, and midbrain. The integration of sensory evidence occurs in sparse neural populations that drive movement-preparatory activity. Visual responses evolve from transient activations in sensory areas to sustained representations in frontal-motor cortex, thalamus, basal ganglia, midbrain, and cerebellum, enabling parallel evidence accumulation. In areas that accumulate evidence, shared population activity patterns encode visual evidence and movement preparation, distinct from movement-execution dynamics. Activity in movement-preparatory subspace is driven by neurons integrating evidence, which collapses at movement onset, allowing the integration process to reset. Across premotor regions, evidence-integration timescales were independent of intrinsic regional dynamics, and thus depended on task experience. Learning aligns evidence accumulation to action preparation in activity dynamics across dozens of brain regions, leading to highly distributed and parallelized sensorimotor transformations during decision-making. This work unifies concepts from decision-making and motor control fields into a brain-wide framework for understanding how sensory evidence controls actions. The study shows that sensory evidence is transformed into goal-directed actions through widespread, distributed, and parallelized neural processes. The findings highlight the role of learning in shaping these processes and the importance of brain-wide dynamics in linking sensation to action during decision-making.