Background: Heart failure (HF) is a condition that afflicts more than 26 million patients worldwide and is associated with high rates of morbidity, mortality, and hospital admissions. Education delivered online is an acceptable and scalable strategy to support patient self-care. Further, gamification, otherwise known as serious games, is gaining acceptance as a valid method of creating behaviour change in education and eHealth. The purpose of this study was to design and pilot test the efficacy of utilizing a theory-informed, web-based, gamified, self-care education website for patients living with HF. Story-based scenarios and rewards were the gamification tactics chosen for the website. Research Design: This study was a three-part, mixed-methods study that included embedded exploratory and explanatory qualitative phases during the intervention design and testing. After the design and initial iteration of the website, 19 patients participated in a pre-post-test design using the Self-Care of Heart Failure Index (SCHFI) and the Dutch Heart Failure Knowledge Scale. Usability measures were tracked using Google Analytics and the System Usability Scale (SUS). Finally, six post-test explanatory qualitative interviews were conducted. Results: There were significant increases in HF knowledge following the intervention despite high baseline knowledge scores (p = 0.04). Post-intervention self-reported HF self-care behaviours were also significantly improved; maintenance (p = 0.005), management (p = 0.003) and confidence (p = 0.003). However, knowledge and self-care scores were not correlated. Patients scored the website as highly usable and described acceptance and varied support for distinct gamification techniques used on the website. Discussion: Although the sample may not have been representative, patients successfully engaged independently with the online self-care education. Explanatory patient interviews confirmed the theoretical explanation for self-care behaviour change in patients' discussion of practised decision making using the engaging content. Behaviour changes independent of knowledge gains is supported by improved decision-making confidence through narrative, scenario-based learning. Using this embedded qualitative, mixed-methods approach, we found that a gamified website that uses narrative and reward-based gamification techniques has the potential to improve HF patient knowledge and self-care. However, more research is needed to confirm the clinical benefit of these results and to address technology literacy inequities.