Background Spinal fusion surgery is a common and painful musculoskeletal surgery performed in the adolescent population. Despite the known risk for developing chronic postsurgical pain, few perioperative psychosocial interventions have been evaluated in this population, and none have been delivered remotely (via the Internet) to improve accessibility. Aims The aim of this single-arm pilot study was to evaluate the feasibility and acceptability of the first Internet-based psychological intervention delivered during the perioperative period to adolescents undergoing major spinal fusion surgery and their parents. Methods Thirteen adolescents (M age = 14.3; 69.2% female) scheduled for spine fusion surgery and their parents were provided access to the online psychosocial intervention program. The program included six lessons delivering cognitive-behavioral therapy skills targeting anxiety, sleep, and acute pain management during the month prior to and the month following surgery. Feasibility indicators included recruitment rate, intervention engagement, and measure completion. Acceptability was assessed via quantitative ratings and qualitative interviews. Results Our recruitment rate was 81.2% of families approached for screening. Among participating adolescent–parent dyads, high levels of engagement were demonstrated (100% completed all six lessons). All participants completed outcome measures. High treatment acceptability was demonstrated via survey ratings and qualitative feedback, with families highlighting numerous strengths of the program as well as areas for improvement. Conclusions These findings suggest that this online psychosocial intervention delivered during the perioperative period is feasible and acceptable to adolescents and their parents. Given favorable feasibility outcomes, an important next step is to evaluate the intervention in a full-scale randomized controlled trial.