Organic light-emitting diode (OLED) display has been widely used for mobile devices due to its features of wide color range and high contrast. However, display systems dominate the significant power consumption of mobile devices that limit its usage time. Hence, this paper proposes a visual-attention-based pixel dimming (VAB-PD) technique to achieve power saving for real-time video displaying on OLED mobile devices. First, the proposed method extracts motion vector (MV) array from the bitstream. Next, considering the perception of human vision to moving objects, a saliency map is calculated from the MV array. Finally, a pixel dimming function is designed to reduce the brightness of the pixels lying in the unnoticeable parts of the video frames, thereby elevating the energy efficiency without deteriorating the visual quality. In addition, an absolute category rating 11-grade scale (ACR11) subjective visual quality test is conducted to determine the optimal coefficient for the dimming function. The experimental results demonstrate that VAB-PD can accomplish 13% of power reduction on average while maintaining acceptable visual quality.