Repeated nicotine exposure can lead to cognitive changes, including working memory. However, we have a limited understanding of such changes. To address this gap, 48 smokers participated in smoking-specific N-back tasks involving smoking and neutral cues under different working memory loads (1-back and 2-back), while EEG data were recorded. By employing drift–diffusion model and EEG analysis, we examined how cue types and working memory loads modulate behavioral performance and identified the underlying cognitive processes and neural correlates. The results showed decreased accuracy across working memory loads and slower reaction times specifically in the low working memory load condition when exposed to smoking cues. Drift-diffusion model analysis suggested that these effects may stem from reduced drift rate and a lower decision threshold. These behavioral differences between cue types were mirrored in the neural activity, with smoking cues eliciting smaller P300 amplitudes, decreased alpha and beta power under both working memory loads, and increased positive slow wave predominantly at low working memory load. Furthermore, negative correlations were observed between nicotine craving and behavior performance (i.e., accuracy), drift–diffusion model parameters (i.e., drift rate and decision threshold) and EEG data (i.e., alpha and beta power). These findings enhance our understanding of how smoking cues affect cognitive processing and the neural mechanisms of working memory in smokers.