ImportancePatients who have been treated for high-grade cervical intraepithelial neoplasia (CIN grade ≥2) are at a high risk for subsequent CIN and other cancers and diseases related to human papillomavirus (HPV). HPV vaccination can reduce the risk of subsequent disease in patients surgically treated for grade 2 or greater CIN; however, there is no formal recommendation for prophylactic HPV vaccination in this high-risk population, and the cost-effectiveness is unknown.ObjectiveTo assess the incremental lifetime outcomes, costs, and cost-effectiveness of integrating peritreatment 9-valent HPV (9vHPV) vaccination in combination with posttreatment surveillance for the prevention of cervical cancer and other HPV-attributable diseases in patients surgically treated for grade 2 or greater CIN vs posttreatment surveillance alone from a UK payer perspective.Design, Setting, and ParticipantsThis economic evaluation used 3 independent Markov model structures. Model inputs for vaccine efficacy, utilities, and costs were obtained from published sources, and cervical cancer screening data were obtained from the National Health Service Cervical Screening Program. Costs were adjusted to 2022 to 2023 reference years. Data were analyzed from October 2022 to September 2023.ExposurePeritreatment vaccination with 9vHPV in combination with posttreatment surveillance compared with posttreatment surveillance alone.Main Outcomes and MeasuresClinical outcomes included grade 1, 2, or 3 CIN; cervical cancer; vaginal cancer; vulvar cancer; anal cancer; head and neck cancer; genital warts; and recurrent respiratory papillomatosis. Incremental cost-effectiveness ratios (ICERs) using a willingness-to-pay threshold (WTP) of £20 000 (US $26 200) per quality-adjusted life-year (QALY) were estimated. Deterministic sensitivity analysis and probabilistic sensitivity analysis were performed.ResultsVaccination with 9vHPV in conjunction with posttreatment surveillance was cost-effective, with a favorable ICER of £13 789.07 (US $18 064.68) per QALY gained (ie, below the WTP of £20 000 per QALY) vs posttreatment surveillance alone. The resulting ICER was £52 358.01 (US $68 588.99) per HPV-related cancer averted and £64 090 (US $83 958.18) per HPV-related cancer death averted. The ICER was most sensitive to discount rate, incidence of HPV infection, vaccine price, and age at initial treatment for grade 2 or greater CIN. Results of the probabilistic sensitivity analysis showed peritreatment 9vHPV vaccination was cost-effective at the WTP recommended by the UK’s Joint Committee on Vaccination and Immunisation (90% of iterations <£30 000 [US $39 300] per QALY) in 100% of iterations.Conclusions and RelevanceThese findings suggest that peritreatment prophylactic 9vHPV vaccination is a cost-effective option for preventing subsequent HPV-attributable diseases in patients surgically treated for grade 2 or greater CIN.