Purpose This study aims to investigate the effects of trunk stability on enhancing postural control and its effects on upper limb function in stroke. Methods This study was designed as a single-case research, with interventions provided 3 times a week for a duration of 3 weeks. Evaluations to assess the effectiveness of the intervention included changes in body posture alignment based on analysis of posture alignment, functional reach test (FRT), postural assessment scale for stroke (PASS), and manual function test(MFT). Results There was an improvement in overall body alignment, becoming more symmetrical. Additionally, the results from the PASS, FRT, and MFT indicate significant enhancements in the subject postural control, and upper extremity function following the intervention. Conclusion Improved trunk stability positively affects upper extremity function in stroke patients by helping maintain the body's center of gravity.