Distal humerus fractures are complex intra-articular injuries commonly managed with Open Reduction and Internal Fixation. Post-operative elbow stiffness is a frequent complication, particularly when immobilisation is prolonged or rehabilitation is delayed. Recovery may be further complicated in individuals with pre-existing neurological conditions such as cerebral palsy and intellectual disability. A 54-year-old right-hand dominant female with a history of cerebral palsy and moderate intellectual disability sustained a distal humerus fracture following a fall and underwent ORIF. The elbow was immobilised for three months, and structured physiotherapy was not initiated until approximately five months post-operatively. On assessment, the patient presented with pain (6/10), marked restriction of elbow range of motion, extension lag of 15°, reduced muscle strength (Grade 3), and significant functional limitations in activities of daily living. A structured 12-week physiotherapy program was implemented, consisting of phased manual therapy, progressive resistance training, and task-oriented functional rehabilitation delivered 4–5 sessions per week. Following intervention, pain resolved (0/10), active elbow flexion improved from 15°–60° to 0°–110°, extension lag resolved completely, passive range of motion increased significantly, and muscle strength improved to Grade 4+. Functional ability, measured using the Patient-Specific Functional Scale, improved from 3 to 8. No adverse events were reported. This case demonstrates that substantial functional recovery is achievable even when physiotherapy is initiated in a delayed post-operative period, including in patients with neurological comorbidities. Structured, progressive, and task-oriented rehabilitation remains effective in restoring mobility and independence despite delayed intervention.