Activity of sensory neurons is influenced not only by external stimuli but also by the animal’s behavioral state. It is well documented that behavior influences the general properties of neural activity, such as response gain. However, it is not known whether it could affect the sensory tuning of individual neurons in a more refined way and what the functional benefit of such nuanced modulation might be. Here, we investigate this in the mouse visual cortex, where sensory response gain varies with locomotion speed. First, using numerical simulations, we demonstrate that gain modulation can multiplex behavioral information in sensory populations, without compromising the accuracy of sensory coding. To implement such multiplexing, behavioral signals should modify the sensory tuning in individual neurons. Second, we analyze neural activity in the mouse visual cortex made available by the Allen Brain Observatory. Our analysis indicates that, in agreement with the theory, locomotion-induced gain modulation can modify the tuning of sensory neurons to direction of visual motion. In that way, the visual cortex could instantiate an accurate, joint representation of sensory and movement-related signals and support computations that simultaneously require both types of information.