While dark mode—bright text on a dark background—is increasingly popular, concerns about its impact on visual performance are growing. Grounded in cognitive psychology and theories of visual attention, this study examined whether contrast polarity (positive polarity: dark text on a bright background, or “light mode”; negative polarity: bright text on a dark background, or “dark mode”) influences visual search performance and distractor suppression. Participants completed a letter search task under both polarity conditions, with task-irrelevant face distractors presented. Response times (RTs) and accuracy rates (ARs) were recorded, and attentional capture rates (ACRs) were measured using eye-tracking to assess visual search performance and distractor suppression. Consistent with prior research, RTs were significantly faster with positive polarity, indicating an advantage in processing relevant stimuli. However, distractor presence had no significant effect on RTs or ARs, and no interaction with contrast polarity emerged. These results suggest that contrast polarity enhances target processing but does not influence distractor suppression under the present conditions. The findings have practical implications for display design, supporting the use of light mode when search speed is critical. Future research should employ more salient distractors and ecologically valid tasks to further explore contrast polarity’s role in visual performance.