Background: Preterm born children are at high risk for adverse motor neurodevelopment. The aim of this study was to establish the relationship between motor outcome and advanced magnetic resonance imaging (MRI) and electroencephalography (EEG) measures. Methods: In a prospective cohort study of 64 very preterm born children, the motor outcome was assessed at 9.83 (SD 0.70) years. Volumetric MRI, diffusion tensor imaging (DTI), and EEG were acquired at 10.85 (SD 0.49) years. We investigated associations between motor outcome and brain volumes (white matter, deep gray matter, cerebellum, and ventricles), white matter integrity (fractional anisotropy and mean, axial and radial diffusivity), and brain activity (upper alpha (A2) functional connectivity and relative A2 power). The independence of associations with motor outcome was investigated with a final model. For each technique, the measure with the strongest association was selected to avoid multicollinearity. Results: Ventricular volume, radial diffusivity, mean diffusivity, relative A2 power, and A2 functional connectivity were significantly correlated to motor outcome. The final model showed that ventricular volume and relative A2 power were independently associated with motor outcome (B = −9.42 × 10−5, p = 0.027 and B = 28.9, p = 0.007, respectively). Conclusions: This study suggests that a lasting interplay exists between brain structure and function that might underlie motor outcome at school age. Impact: This is the first study that investigates the relationships between motor outcome and brain volumes, DTI, and brain function in preterm born children at school age.Ventricular volume and relative upper alpha power on EEG have an independent relation with motor outcome in preterm born children at school age.This suggests that there is a lasting interplay between structure and function that underlies adverse motor outcome.