Aim: The study aimed to investigate the effectiveness of a web-based therapy programme, ‘Move it to improve it’ (Mitii™), in children with unilateral cerebral palsy (UCP) on occupational performance, upper limb function, and visual perception. Method: Participants (n=102) were matched in pairs and randomized to intervention (Mitii for 20wks; 26 males, mean age 11y 8mo [2y 4mo], Manual Ability Classification System level I=11, II=39, III=1) or control (standard care; 25 males, mean age 11y 10mo [2y 5mo], Manual Ability Classification System level I=13, II=37). Outcomes were the Assessment of Motor and Process Skills (AMPS), Assisting Hand Assessment, Jebsen–Taylor Test of Hand Function (JTTHF), Melbourne Assessment of Unilateral Upper Limb Function (MUUL), Canadian Occupational Performance Measure (COPM), and Test of Visual Perceptual Skills (TVPS-3). Results: Participants completed on average 32.4 hours of Mitii (range 3.7–74.7h). The Mitii group demonstrated significantly greater post-intervention scores than the comparison group on the AMPS, JTTHF dominant upper limb, COPM, and TVPS-3. The differences between groups were not clinically significant. There were no differences between groups on measures of impaired upper limb function. Interpretation: Mitii delivers individualized, web-based therapy at home and has potential to increase therapy dose. Mitii can be considered as an option to enhance occupational performance and visual perception for children with UCP.