<p>Mirror-assisted strategies are commonly used in the rehabilitation training of patients with hemiparesis in the upper limbs following a stroke. Traditional robotic mirror assistance focuses on achieving high-precision mirror trajectory tracking, often neglecting the issue of active movement in the affected side. This paper proposes a task performance-based adaptive impedance control, where the robot assists the affected side in an assist-as-needed manner, thereby encouraging the patient to perform active movements. To account for inter-individual variability, a method for assessing the affected side’s motor performance, based on the healthy side’s movement level, is introduced. Adaptive impedance control is then constructed based on the motor performance of the affected side, enabling the robot to provide adaptive assistance force. Eight healthy participants were recruited for experimental testing. Experimental results show that when the robot provides mirror-based assist-as-needed to the affected side, the robot’s stiffness coefficient and assistance force are positively correlated with the motor assessment coefficient of the affected side, thereby verifying the feasibility of the proposed strategy. This study offers a robotic-assisted rehabilitation strategy for stroke patients that balances active participation and individual adaptability, with the potential to enhance rehabilitation outcomes and enable precise rehabilitation interventions.</p>