BACKGROUND: Optimal approaches to promote sustained adherence to lifestyle and bodyweight recommendations in postmenopausal breast cancer (PMBC) survivors are lacking. PURPOSE: This Delphi-study aims to identify and understand expert-opinion on potential barriers and facilitators for promoting adherence to these lifestyle and bodyweight recommendations in (clinical) care for PMBC survivors, and to determine potential effective intervention strategies. METHODS: The expert panel consisted of oncology Health Care Professionals (HCPs) (N = 57), patient advocates (N = 5), and PMBC survivors (N = 38). They completed three questionnaires: Q1-idea generation; Q2-validation and prioritization; Q3-ranking. The Behavior Change Wheel was used as theoretical framework for analysis. Thematic analysis was applied to identify key overarching themes based on the top-ranked facilitators and barriers. Potential Behavior Change Techniques (BCTs) and intervention strategies were identified using the Behavior Change Technique Taxonomy version 1 and the Behavior Change Wheel. RESULTS: Eleven core categories of key barriers/facilitators for the promotion of adherence to recommendations for lifestyle and bodyweight among PMBC survivors were identified. For each core category, relevant BCTs and practical potential intervention strategies were selected based on suggestions from the expert panel. These included: increasing knowledge about the link between lifestyle and cancer; enabling self-monitoring of lifestyle behaviors followed by evaluation; offering group lifestyle counseling for PMBC survivors, enhancing social support for favorable lifestyle behaviors; and stimulating multidisciplinary collaboration among HCPs. CONCLUSIONS: Findings provide valuable insight for the development of interventions changing behavior of PMBC survivors and HCPs toward increased healthy lifestyle (support) behavior.