Motor inhibition-a key aspect of cognitive control-is crucial in interactive contexts, where partners must suppress and adjust actions for optimal coordination. Previous findings have shown that the presence of a human partner impairs motor inhibition in joint action tasks. This study investigated whether a similar effect would occur when replacing the human partner with a humanoid robot. To do so, we conducted four experiments using a Stop-Signal Task: (a) a non-engaging robot condition, (b) an engaging robot condition, (c) an engaging robot with disabled cameras, and (d) a human partner condition. Results showed that a humanoid robot does not impair motor inhibition, in contrast to human partners. Instead of increasing cognitive demands, the presence of a humanoid robot appeared to enhance attentional focus when perceived as monitoring, leading to improved motor inhibition. These findings suggest that humanoid robots can be integrated into joint action tasks without compromising cognitive control. Thus, we conclude that, if implemented ethically, robots could offer advantages in collaborative tasks where humans cannot, highlighting their potential for enhancing human performance in shared activities.