This paper studies the signal to noise ratio (SNR) statistics of mobile users with random orientations in an indoor visible light communication (VLC) system. The considered system model consists of an access point (AP) and a mobile user device (UD) with a random orientation, which makes the instantaneous received SNR random. The distance between the AP and the UD is modeled through the random waypoint (RWP) mobility model, whereas uniform incidence angle is used to model the random orientation of the UD. Novel closed- form expressions for the probability density function and the cumulative distribution function of the instantaneous received SNR are derived. Based on this, closed-form expressions of typical performance measures, such as the outage rate probability (ORP) and the average symbol error probability (SEP) are also derived. The accuracy of the derived expressions are validated through extensive simulations and the effect of mobility and random orientation of the UD on the performance of the system are then evaluated. Our results show that the UD's random orientation degrades the system performance.