Objective: To investigate the effect of an information-knowledge-attitude-practice (IKAP) nursing intervention on the caregiving capacity of family caregivers of elderly dementia patients. Methods: Sixty-nine family caregivers of elderly dementia patients attending the neurology outpatient clinic of a hospital between October 2024 and March 2025 were selected. They were randomly divided into a control group (n = 35) and an observation group (n = 34). The control group received routine health education, while the observation group additionally underwent a systematic Information-Knowledge-Attitude-Practice (IKAP) nursing intervention. Care competence and self-efficacy scores were compared between groups before intervention and after 12 weeks. Results: Pre-intervention, no statistically significant difference existed in care competence or self-efficacy scores between groups (p > 0.05). Following the 12-week intervention, all scores significantly increased in both groups, with the observation group demonstrating superior outcomes compared to the control group (p < 0.001). Conclusion: The care intervention program based on the IKAP model effectively enhances caregivers’ care competence and self-efficacy, thereby positively promoting the quality of life for patients with dementia.