AimTo explore the associations between depression, anxiety, decisional conflict and advance care planning engagement and the potential mediating role of decisional conflict in the associations between depression, anxiety and advance care planning among community‐dwelling older adults.DesignA cross‐sectional study was conducted with 262 community‐dwelling older Australians across metropolitan, regional and rural communities between August and October 2022.MethodsValidated self‐reported questions were used to collect data on anxiety, depression (Hospital Anxiety and Depression Scale), decisional conflict (Decisional Conflict Scale), advance care planning engagement (Advance Care Planning Engagement Survey) and covariates (demographic characteristics, health literacy [Health Literacy Screening Questions]), overall health status (Short form 36). Data analysis included descriptive statistics, bivariate association analysis, general linear modelling and path analysis.ResultsAnxiety and decisional conflict were directly associated with advance care planning engagement even after controlling for potential effects of demographic characteristics, health literacy and overall health status. The model, including age, gender, country of birth, language spoken at home, education, overall health status, anxiety, depression, decisional conflict and interaction between anxiety and decisional conflict, explained 24.3% of the variance in their advance care planning engagement. Decisional conflict mediated the association between anxiety and advance care planning engagement.ConclusionIncreased anxiety and decisional conflict were associated with reduced advance care planning engagement directly, even among community‐dwelling older adults with higher levels of education and health literacy. Increased anxiety was associated with reduced advance care planning engagement indirectly via increased decisional conflict. Healthcare professionals should assess community‐dwelling older adults' anxiety and implement interventions to manage their anxiety and decisional conflict, as these may facilitate their engagement in advance care planning.ImpactUnderstanding factors associated with advance care planning engagement among community‐dwelling older adults may inform strategies facilitating their future engagement in advance care planning. Findings from this study may be used as evidence for future implementation to facilitate the engagement of community‐dwelling older adults in advance care planning.Reporting MethodThe STROBE statement checklist was used as a guide to writing the manuscript.Patient or Public ContributionThe study was advertised publicly through social media (e.g. Twitter and Facebook) and newsletters (e.g. Advance Care Planning Australia, Centre for Volunteering, Palliative Care Australia and a large home care service provider with approximately 7000 older clients receiving support or services) to recruit participants. People aged 65 years and older living independently in the Australian community who could communicate in English were invited to participate and answer the questionnaire.