Difficulties in controlling emotions - a proxy for emotion dysregulation (ED)-and difficulties in expressing feelings in words-'absence of emotion labelling' or alexithymia-co-exist in autism and contribute to elevated levels of impulsive and suicidal behaviour. To date, studies linking the two phenomena have relied on retrospective self-reported measures, lacking support for generalizability to real-life situations. The present study investigated in vivo emotion labelling and its impact on emotion control in 29 autistic adults without intellectual disability (ASC) and 28 neurotypical (NT) individuals of similar age, sex, and educational level. Participants were trained in an Ecological Momentary Assessment (EMA) to label their emotions, the arousal dimension, and their emotion control via smartphone over a one-week period. Findings showed that the ASC group experienced more instances of 'having an emotion that I cannot name' and, when they were able to label their emotions, they reported higher rates of negative and conflicting (simultaneously positive and negative) emotions. In both groups, the absence of emotion labelling, and intense negative emotions were associated with impaired emotion control. However, the association between lack of emotional awareness-'I have no emotion'-and impaired emotion control was only evident in ASC individuals. Our study highlights a nuanced facet of emotional processing in the ASC population. Further research is needed to gain a deeper understanding of the complex relationship between ED and alexithymia in autism.