PurposeThe purpose of this study was to reveal the interrelationships between residents’ perceived trust, perceived social and personal benefits and event support intention for the Tokyo Olympic and Paralympic Games. The interrelationships were investigated over time.Design/methodology/approachData were collected twice (Time 1: 7–9 September 2021 and Time 2: 7–9 September 2022) using a panel design. Stratified online sampling was employed based on resident status, age and Olympic and Paralympic viewership (n = 714). Structural equation modelling was employed to analyse the data.FindingsTrust strongly affected personal and social benefits at Time 1 and event support at Time 2. However, social benefits at Time 2 did not significantly influence event support at Time 2. The reciprocal effects of personal and social benefits at Time 1 and Time 2 were observed to be weakly related or not related.Practical implicationsBidding procedures often require public backing. Actors must explain how residents will be affected generally and which benefits might derive from the megasport event. Briefings would also boost event openness. Messages that locals can apply to their own lives are more important than explaining how society will change.Originality/valueThis study contributed to the literature by applying the concepts of trust and buy-in from social exchange theory to the context of mega-sporting events. The findings highlighted that the success of such events hinged on resident buy-in. Contrary to previous studies, this research clarified that while residents may have distrusted certain entities, they still supported the event, indicating that trust and buy-in operated independently.