Social anxiety disorder (SAD) is marked by intense anxiety in social situations and negative cognitions. We developed the Social Anxiety-Awareness and Acceptance Scale (SA-AAS) to measure awareness and acceptance in anxiety-provoking social situations and examined the relationship between awareness, acceptance, and SAD symptoms. Patients (N = 412) with SAD completed the SA-AAS and a set of questionnaires that evaluated trait mindfulness, self-focused attention, cost/probability bias, avoidance behavior, and social anxiety. An exploratory factor analysis revealed that the SA-AAS has two factors: "awareness" and "acceptance." Correlation analyses revealed that each factor had a significantly weak-to-moderate correlation with the total score for trait mindfulness and the observing, non-reactivity, and describing factors. Partial correlation analyses demonstrated no significant correlations between awareness and cost/probability bias, avoidance behavior, and social anxiety. In contrast, there were significant negative correlations between acceptance and self-focused attention, cost/probability bias, avoidance behavior, and social anxiety. A one-way analysis of variance indicated that the low awareness and acceptance cluster, and the high awareness and low acceptance cluster had higher SAD symptom scores concerning cost/probability bias and social anxiety than the moderate and high awareness and acceptance clusters. The SA-AAS has high reliability and validity, and acceptance of mindfulness was negatively related to SAD symptoms.