Attachment plays an important role in emotional experience, interaction, and regulation, particularly in close relationships. Specifically, individuals with higher attachment-related anxiety and avoidance tend to report more psychological distress in general compared to more securely attached counterparts, but less is known about their emotional experience in daily life. We employed the experience sampling method to assess whether the individual variability in attachment-related anxiety and avoidance relates to momentary affective experience, stress, and perceived closeness to others in everyday social contexts. The research sample consisted of a total of 44 healthy individuals (23 females and 21 males) between ages 18-40 years. Participants were administered the Experience in Close Relationships-Revised (ECR-R) and received a mobile device with pre-installed application that signalled them randomly 10 times per day for 6 days to complete questionnaires about their current experiences and social context. Individuals with higher attachment-related anxiety reported overall increase of negative affective states and stress in daily life. Attachment-related avoidance, on the other hand, was associated with an overall decrease of positive affective states with negative impact on the ability to benefit from proximity to others. These results indicate that a relatively stable attachment dimension translates to mental states fluctuations and social interactions in daily life, thus adding crucial ecological validity to the attachment theory.