This study investigated the upper extremity functions of children with Cerebral Palsy (CP) and the association between upper extremity function and trunk control. Thirty children with unilateral CP and 32 children with bilateral CP between the ages of 5 and 12 years were included in this study. The Trunk Control Measurement Scale (TCMS) was used to assess trunk control, and the Quality of Upper Extremity Skills Test was used to assess upper extremity functions (QUEST) (QUEST consists of four subscales: Dissociated Movements Scale, Grasp Scale, Weight Bearing Scale, and Protective Extension Scale). There was a significant difference between the unilateral and bilateral CP groups, with unilateral CP favored in terms of trunk control. There was no difference in QUEST total scores between the unilateral and bilateral CP groups (p < 0.05). In both groups, there was a significant correlation between the total TCMS score and the Dissociated Movements Scale, Grasp Scale, Weight Bearing Scale and QUEST total score (p < 0.05). There was a significant positive correlation between trunk control and upper extremity functions in children with CP. This relationship must be considered for the effective implementation of physiotherapy assessment and intervention.