ABSTRACT Background Experiential avoidance (EA) may serve as a risk factor for a wide range of anxiety-related psychopathology. Anxiety is thought to trigger the use of EA, while also serving as a consequence of EA efforts. Previous ecological momentary assessment (EMA) studies found that EA was associated with greater anxiety in nonclinical undergraduates and patients with social anxiety disorder. Methods The present study examined the in-the-moment, bidirectional relationship between EA, perceived stress, and two facets of anxiety (autonomic arousal and worry/misery) in a sample of treatment-seeking patients broadly diagnosed with an anxiety-related disorder (N = 46). Participants completed a baseline assessment followed by an EMA assessment period (assessments three times daily for seven days). We hypothesized that there would be a bidirectional relationship between EA and anxiety/stress. Results Results largely supported a unidirectional relationship such that greater EA at one time point predicted higher stress at a later time point controlling for previous stress levels and linear time. Trend-level associations between EA and anxiety symptoms are discussed. Conclusions The current study provides important insight into the relationship between EA and anxiety symptoms in a clinical sample of participants with anxiety-related disorders.