<p>This study aimed to investigate the knowledge, attitudes, and practices (KAP) regarding melanoma among melanoma patients and their family members. A cross-sectional survey was conducted from April 1, 2023, to March 1, 2024, in hospitals nationwide. Sociodemographic data and KAP scores were assessed through the administered questionnaires. A total of 481 valid questionnaires were included, with 241 (50.10%) identified as patients themselves. The mean scores for knowledge, attitude, and practice were 12.25 ± 5.70 (range: 0–24), 22.87 ± 2.59 (range: 7–35), and 24.46 ± 4.91 (range: 6–30), respectively. Correlation analysis revealed significant positive associations between knowledge and attitude (<i>r</i> = 0.319, <i>P</i> &lt; 0.001), as well as knowledge and practice (<i>r</i> = 0.319, <i>P</i> &lt; 0.001). Additionally, a correlation was observed between attitude and practice (<i>r</i> = 0.353, <i>P</i> &lt; 0.001). Structural equation modeling (SEM) results demonstrated a direct effect of knowledge on both attitude (β = 0.442, <i>P</i> &lt; 0.001) and practice (β = 0.174, <i>P</i> = 0.008), as well as an effect of attitude on practice (β = 0.832, <i>p</i> &lt; 0.001). Patients with melanoma and their family members exhibit inadequate knowledge but positive attitudes and proactive practices towards melanoma. Efforts should be directed towards enhancing educational initiatives tailored to improve knowledge about melanoma among patients and their families, thereby reinforcing their already positive attitudes and practices towards melanoma.</p>