Background Avoidable 30-day hospital readmission is a key policy problem among health systems globally, including Hong Kong. Among all health conditions, heart failure (HF) and chronic obstructive pulmonary disease (COPD) are two leading causes for such readmissions. Effectiveness of peri-discharge complex interventions for reducing such readmissions among patients with HF or COPD has been synthesized in network meta-analyses (NMAs). However, because benefits of complex interventions may vary across health system contexts, evidence-based complex interventions should be adapted before implementation. Objectives To select and refine peri-discharge complex interventions for reducing 30-day hospital readmissions among HF and COPD patients in the Hong Kong public healthcare system context using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) Evidence to Decision (EtD) framework, based on local stakeholders’ consensus. Methods Two 18-participant panels were recruited to carry out a two-step process for both conditions separately. In Step 1, participants were invited to prioritize NMA-supported complex interventions and suggest important combinations of different complex interventions. In Step 2, based on this priority list, participants were invited to conduct a two-round Delphi study for generating a list of consensus-based complex interventions for reducing 30-day hospital readmissions. GRADE EtD framework was used to guide the decision-making process, taking into consideration benefits, harms, values and preferences, equity, acceptability, and feasibility. Results Five and six out of ten complex interventions reached positive consensus for HF and COPD, respectively. Case management, discharge planning, patient education, self-management, and telephone follow-up were common components for both conditions and were considered as core elements for reducing 30-day hospital readmissions. Preliminary implementation barriers are in the areas of governance and leadership, financing, health workforce development, service access, and readiness, as well as empowerment of patients and caregivers. Conclusions This study has successfully applied the GRADE EtD framework for starting the adaptation process of complex interventions and has established a list of local stakeholders-endorsed complex interventions for reducing 30-day hospital readmissions. Before scaling up these complex interventions in the Hong Kong health system, further studies for improving intervention-context fit and assessing real world implementation effectiveness are needed.