Alexithymia is associated with a lack of flexibility at several stages of emotion regulation. Additionally, previous studies associated higher alexithymia with particularities in emotional facial expression perception, and with lower executive performance. The objective of the study was to explore the cognitive factors that may underlie the lack of flexibility associated with emotion regulation in alexithymia. One hundred and twenty-six non-clinical adults underwent Go/no-Go tasks with neutral and emotional material (positive and negative emotional facial expressions of low vs. high arousal levels). The results first show that emotional stimuli had an effect on inhibition that was differentiated according to both valence and arousal levels. Alexithymia scores were never associated with executive performance in neutral blocks but moderated the effect of emotional stimuli depending on the valence and arousal combination in emotional blocks. Most of the moderation effects led to higher performances: higher alexithymia scores moderated the effect of emotional stimuli on inhibitory and perceptual performances, but direction of effects, facets and emotional stimuli involved are not consistent. We discuss the implications of these findings in terms of emotional salience effects on cognition and their potential role in alexithymia.