Abstract Introduction Deprescribing, the systematic process of stopping or altering inappropriate medicines, has been suggested as a safe, effective and appropriate process to optimise prescribing for older adults (1). There is still a lack of understanding of how best to implement sustainable deprescribing in long-term care (LTC). Aim Design a theory-driven implementation strategy, based on consensus from healthcare professionals (HCPs), to facilitate their engagement with deprescribing for frail older adults in LTC. Methods This study consisted of three phases and was designed in conjunction with HCPs working in LTC. Firstly, barriers and enablers to deprescribing in LTC previously identified by the research team were mapped to behaviour change techniques (BCTs) (2). Secondly, a Delphi survey of HCPs (General Practitioners (GPs), Pharmacists, nurses, geriatricians and psychiatrists of old age) was conducted to select feasible BCTs to support deprescribing. HCPs were purposively sampled and recruited via email, divided into HCPs working in Ireland and internationally. Experts were identified from existing professional relationships, engagement with LTC or deprescribing research. Using the results from the Delphi process, the literature on deprescribing interventions and research team knowledge, the BCTs which could form components of an intervention in LTC were shortlisted based on was acceptability, effectiveness, affordability, safety and equity (APEASE). Finally, a roundtable discussion was held with a purposeful, convenience sample of GPs, Pharmacists and nurses working in LTC in Ireland, to prioritise the previously identified barriers/enablers and operationalise the proposed deprescribing strategies created from feasible BCTs and identify the most important strategy to facilitate deprescribing. Results Overall, 34 BCTs were mapped to previously identified barriers/enablers to deprescribing in LTC. For the Delphi survey, 33 HCPs were invited, 20 agreed and it was completed by 16 participants. The Delphi consisted of two rounds. Participants reached consensus that 26 of the BCTs could feasibly be implemented in LTC. Following the APEASE assessment, 21 BCTs were considered eligible for operationalisation. The roundtable discussion, consisting of eight HCPs, identified that lack of resources (time, staffing, technology), was the most important barrier to address. The agreed implementation strategy to enhance engagement with deprescribing processes was an education session prior to a multidisciplinary team (MDT) meeting, led by a nurse from the LTC setting. This was designed from 11 BCTs, including action planning, social support and environmental restructuring addressing the predominant barrier. Incorporating the MDT reduces the burden which would exist if the responsibility was placed on one HCP. Meeting at the LTC site addresses the insufficient technology, as patient information is available. Conclusion This study describes an implementation strategy design process following principles of behavioural and implementation science. Engaging targeted end users throughout the process allows for the creation of a strategy which is intended to address the main perceived barrier to deprescribing of insufficient resources. A limitation of this study is the specificity of the intervention for Irish LTC context, which may have different staffing and organisational structures compared to international healthcare systems.