Children who develop greater negatively-biased recall of pain (ie, recalled pain is higher than the initial pain report) following surgery are at risk for developing chronic pain; therefore, identifying risk factors for the development of biased pain memories is important. Higher anxiety has been implicated in the development of greater negatively-biased recall of pain; however, studies have not examined anxiety at multiple time points before and after a surgery and its relationship to children's postsurgical pain memories after 1 year. This prospective study examined a cohort of 237 children and adolescents undergoing major surgery. Anxiety sensitivity, pain catastrophizing, and pain anxiety were assessed at baseline, 48 to 72 hours after surgery, and at 6- and 12-month follow-ups. Pain intensity at rest, movement-evoked pain intensity, and pain unpleasantness were assessed daily in hospital. Memories for pain were elicited via telephone 1-year post surgery. Findings revealed that children who had higher levels of anxiety at baseline and 48 to 72 hours after surgery developed greater negatively-biased recall of pain intensity 12 months after surgery. Specifically, higher anxiety sensitivity at baseline and greater tendencies to catastrophize about pain at baseline and in the immediate acute recovery phase were most strongly linked to greater negatively-biased recall of pain. Greater negatively-biased recall of pain was related to higher pain intensity at 6 and 12 months post surgery. Findings support conceptual models of anxiety and pain memory biases and can inform intervention efforts to reduce anxiety in the pre- and post-op periods to minimize negative biases in pain memories.