Aim: This study aimed to develop a video-based advance care planning intervention, and examine the effectiveness of the intervention on knowledge, behavioral intentions and advance directive signing among older patients admitted to a geriatric unit in Taiwan. Methods: This randomized controlled trial was carried out in two geriatric wards of a medical center in northern Taiwan, between June 2014 and June 2015. The participants were randomly assigned to the intervention (n = 39) or control (n = 43) group. Participants in the intervention group watched a 5-min video regarding advance care planning. The control group received usual care. Structured questionnaires on advance care planning knowledge and behavioral intentions were administered to both groups before and after the intervention. Advance directive signing was carried out until 2 weeks after hospital discharge through a chart review. Results: The intervention group showed a significantly higher advance care planning knowledge score and behavioral intention score than the control group post-intervention. The rate of advance directive signing was 33.3% in the intervention group and 9.3% in the control group (P = 0.01). Conclusions: This study showed the effectiveness of video-based interventions in increasing advance care planning knowledge, behavioral intention and advance directive signing among hospitalized older patients. Geriatric wards could use our model to promote advance care planning among older patients. Geriatr Gerontol Int 2021; 21: 478–484.