OBJECTIVES: To conduct a cost-utility analysis of an implementation package that has been developed aiming to embed the referral of people with type 2 diabetes mellitus (T2DM) to structured self-management education (SSME) from primary care into routine practice compared with usual care. DESIGN: Model-based cost-effectiveness analysis using the School for Public Health Research type 2 diabetes treatment model. With costs and effectiveness parameters coming from analyses of data from a cluster randomised control trial. SETTING: English National Health Service. PARTICIPANTS: People with T2DM from 64 GP practices in England. INTERVENTIONS: Embedding SSME implementation package Usual care. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome measure was the incremental cost-effectiveness ratio. Secondary outcome measures included the probability of Embedding implementation package being cost-effective and value of information. RESULTS: The estimated cost of the intervention was £40 316 across the study sites, which equates to £0.521 per patient across all practices. For the base case, the estimated mean discounted incremental lifetime cost of the intervention per patient is £48.19. This is associated with a mean per patient incremental quality-adjusted life-year (QALY) estimate of 0.006, producing an incremental cost-effectiveness ratio of £8311 per QALY gained. This has a 73.1% probability of the intervention being cost-effective at a funding threshold of £20 000 per QALY gained. Scenario analyses indicate that alternative parameterisations can lead to this finding being overturned. CONCLUSIONS: The effectiveness of the Embedding packages was hampered by the COVID-19 pandemic. However, our base case analysis shows that Embedding could be cost-effective for this patient population, but this was subject to significant structural uncertainty. This suggests that while implementation initiatives can be highly cost-effective in this population, more robust evidence or further incentivisation will be required before widespread adoption can be recommended. TRIAL REGISTRATION NUMBER: ISRCTN23474120, registered 05/04/2018.