ASMR is a sensory-perceptual experience in which specific audio-visual or haptic stimuli reliably trigger electro-static-like ‘brain tingles’ extending peripherally from the back of the scalp. While generally an under-studied phenomenon, research is beginning to identify potential therapeutic benefits of immersing in ASMR-content, supported by anecdotal accounts from active online communities. The present mixed-methods online study aimed to explore the phenomenological aspects of ASMR and its potential therapeutic effects. A total of 224 participants watched ASMR-videos and completed scales measuring ASMR response and affect. Participants then completed four open-ended questions about their ASMR experience and use. In line with our hypotheses, quantitative results suggested that participants who experienced ASMR demonstrated significantly higher positive affect and significantly lower negative affect compared to those who did not (or were unsure about whether they did) experience ASMR. The pleasurability and intensity of ASMR also positively correlated with measures of positive affect, and negatively with measures of negative affect. Thematic analysis identified great phenomenological variability in perceived pleasurability and intensity of ASMR experience among individuals as a super-theme present across themes (Psychological, Physical and Social dimensions). Based on these findings, a multi-dimensional model for characterising ASMR is proposed, providing clear opportunities for future research.